refactor(ui): IMPL_12 - Migrate Toast notifications to Banner system

Changes:
- SyncProgress.kt: Add INFO phase to SyncPhase enum
- SyncProgress.kt: Update isVisible to always show INFO phase
- SyncStateManager.kt: Add showInfo() and showError() methods
- SyncProgressBanner.kt: Add INFO icon (Icons.Outlined.Info) + secondaryContainer color
- SyncProgressBanner.kt: Add INFO branch in phaseToString()
- ComposeMainActivity.kt: Add auto-hide for INFO phase (2.5s delay)
- MainViewModel.kt: Replace Toast with Banner in deleteNoteFromServer()
- MainViewModel.kt: Replace Toast with Banner in deleteMultipleNotesFromServer()
- NoteEditorViewModel.kt: Import SyncStateManager
- NoteEditorViewModel.kt: Add Banner feedback (INFO/ERROR) in editor deleteNote()
- NoteEditorViewModel.kt: Remove NOTE_SAVED toast (NavigateBack is sufficient)
- NoteEditorViewModel.kt: Remove NOTE_DELETED toast (already done)

All non-interactive notifications now use the unified Banner system.
Server-delete results show as INFO (success) or ERROR (failure) banners.
Snackbars with Undo actions and NOTE_IS_EMPTY validation toasts remain unchanged.

android/app/src/main/java/dev/dettmer/simplenotes/sync/SyncProgress.kt

@@ -52,9 +52,10 @@ data class SyncProgress(
     /**
      * Ob das Banner sichtbar sein soll
      * Silent syncs zeigen nie ein Banner
+     * 🆕 v1.8.1 (IMPL_12): INFO ist immer sichtbar (nicht vom silent-Flag betroffen)
      */
     val isVisible: Boolean
-        get() = !silent && phase != SyncPhase.IDLE
+        get() = phase == SyncPhase.INFO || (!silent && phase != SyncPhase.IDLE)
     
     /**
      * Ob gerade ein aktiver Sync läuft (mit Spinner)
@@ -95,5 +96,8 @@ enum class SyncPhase {
     COMPLETED,
     
     /** Sync mit Fehler abgebrochen */
-    ERROR
+    ERROR,
+    
+    /** 🆕 v1.8.1 (IMPL_12): Kurzfristige Info-Meldung (nicht sync-bezogen) */
+    INFO
 }

android/app/src/main/java/dev/dettmer/simplenotes/sync/SyncStateManager.kt

@@ -245,4 +245,60 @@ object SyncStateManager {
     fun markGlobalSyncStarted(prefs: android.content.SharedPreferences) {
         prefs.edit().putLong(dev.dettmer.simplenotes.utils.Constants.KEY_LAST_GLOBAL_SYNC_TIME, System.currentTimeMillis()).apply()
     }
+    
+    // ═══════════════════════════════════════════════════════════════════════
+    // 🆕 v1.8.1 (IMPL_12): Info-Meldungen über das Banner-System
+    // ═══════════════════════════════════════════════════════════════════════
+    
+    /**
+     * Zeigt eine kurzfristige Info-Meldung im Banner an.
+     * Wird für nicht-sync-bezogene Benachrichtigungen verwendet
+     * (z.B. Server-Delete-Ergebnisse).
+     * 
+     * ACHTUNG: Wenn gerade ein Sync läuft (isSyncing), wird die Meldung
+     * ignoriert — der Sync-Progress hat Vorrang.
+     * 
+     * Auto-Hide erfolgt über ComposeMainActivity (2.5s).
+     */
+    fun showInfo(message: String) {
+        synchronized(lock) {
+            // Nicht während aktivem Sync anzeigen — Sync-Fortschritt hat Vorrang
+            if (isSyncing) {
+                Logger.d(TAG, "ℹ️ Info suppressed during sync: $message")
+                return
+            }
+            
+            _syncProgress.value = SyncProgress(
+                phase = SyncPhase.INFO,
+                resultMessage = message,
+                silent = false  // INFO ist nie silent
+            )
+            
+            Logger.d(TAG, "ℹ️ Showing info: $message")
+        }
+    }
+    
+    /**
+     * Zeigt eine Fehlermeldung im Banner an, auch außerhalb eines Syncs.
+     * Für nicht-sync-bezogene Fehler (z.B. Server-Delete fehlgeschlagen).
+     * 
+     * Auto-Hide erfolgt über ComposeMainActivity (4s).
+     */
+    fun showError(message: String?) {
+        synchronized(lock) {
+            // Nicht während aktivem Sync anzeigen
+            if (isSyncing) {
+                Logger.d(TAG, "❌ Error suppressed during sync: $message")
+                return
+            }
+            
+            _syncProgress.value = SyncProgress(
+                phase = SyncPhase.ERROR,
+                resultMessage = message,
+                silent = false
+            )
+            
+            Logger.e(TAG, "❌ Showing error: $message")
+        }
+    }
 }

android/app/src/main/java/dev/dettmer/simplenotes/ui/editor/NoteEditorViewModel.kt

@@ -13,6 +13,7 @@ import dev.dettmer.simplenotes.models.Note
 import dev.dettmer.simplenotes.models.NoteType
 import dev.dettmer.simplenotes.models.SyncStatus
 import dev.dettmer.simplenotes.storage.NotesStorage
+import dev.dettmer.simplenotes.sync.SyncStateManager
 import dev.dettmer.simplenotes.sync.SyncWorker
 import dev.dettmer.simplenotes.sync.WebDavSyncService
 import dev.dettmer.simplenotes.utils.Constants
@@ -398,7 +399,7 @@ class NoteEditorViewModel(
                 }
             }
             
-            _events.emit(NoteEditorEvent.ShowToast(ToastMessage.NOTE_SAVED))
+            // 🆕 v1.8.1 (IMPL_12): NOTE_SAVED Toast entfernt — NavigateBack ist ausreichend
 
             // 🌟 v1.6.0: Trigger onSave Sync
             triggerOnSaveSync()
@@ -438,17 +439,33 @@ class NoteEditorViewModel(
                         val success = withContext(Dispatchers.IO) {
                             webdavService.deleteNoteFromServer(noteId)
                         }
+                        // 🆕 v1.8.1 (IMPL_12): Banner-Feedback statt stiller Log-Einträge
                         if (success) {
                             Logger.d(TAG, "Note $noteId deleted from server")
+                            SyncStateManager.showInfo(
+                                getApplication<Application>().getString(
+                                    dev.dettmer.simplenotes.R.string.snackbar_deleted_from_server
+                                )
+                            )
                         } else {
                             Logger.w(TAG, "Failed to delete note $noteId from server")
+                            SyncStateManager.showError(
+                                getApplication<Application>().getString(
+                                    dev.dettmer.simplenotes.R.string.snackbar_server_delete_failed
+                                )
+                            )
                         }
                     } catch (e: Exception) {
                         Logger.e(TAG, "Error deleting note from server: ${e.message}")
+                        SyncStateManager.showError(
+                            getApplication<Application>().getString(
+                                dev.dettmer.simplenotes.R.string.snackbar_server_error,
+                                e.message ?: ""
+                            )
+                        )
                     }
                 }
                 
-                _events.emit(NoteEditorEvent.ShowToast(ToastMessage.NOTE_DELETED))
                 _events.emit(NoteEditorEvent.NavigateBack)
             }
         }

android/app/src/main/java/dev/dettmer/simplenotes/ui/main/ComposeMainActivity.kt

@@ -236,6 +236,11 @@ class ComposeMainActivity : ComponentActivity() {
                         kotlinx.coroutines.delay(2000L)
                         SyncStateManager.reset()
                     }
+                    // 🆕 v1.8.1 (IMPL_12): INFO-Meldungen nach 2.5s ausblenden
+                    dev.dettmer.simplenotes.sync.SyncPhase.INFO -> {
+                        kotlinx.coroutines.delay(2500L)
+                        SyncStateManager.reset()
+                    }
                     dev.dettmer.simplenotes.sync.SyncPhase.ERROR -> {
                         kotlinx.coroutines.delay(4000L)
                         SyncStateManager.reset()

android/app/src/main/java/dev/dettmer/simplenotes/ui/main/MainViewModel.kt

@@ -470,12 +470,13 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
                 }
                 
                 if (success) {
-                    _showToast.emit(getString(R.string.snackbar_deleted_from_server))
+                    // 🆕 v1.8.1 (IMPL_12): Toast → Banner INFO
+                    SyncStateManager.showInfo(getString(R.string.snackbar_deleted_from_server))
                 } else {
-                    _showToast.emit(getString(R.string.snackbar_server_delete_failed))
+                    SyncStateManager.showError(getString(R.string.snackbar_server_delete_failed))
                 }
             } catch (e: Exception) {
-                _showToast.emit(getString(R.string.snackbar_server_error, e.message ?: ""))
+                SyncStateManager.showError(getString(R.string.snackbar_server_error, e.message ?: ""))
             } finally {
                 // Remove from pending deletions
                 _pendingDeletions.value = _pendingDeletions.value - noteId
@@ -507,7 +508,7 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
                 }
             }
             
-            // Show aggregated toast
+            // 🆕 v1.8.1 (IMPL_12): Toast → Banner INFO/ERROR
             val message = when {
                 failCount == 0 -> getString(R.string.snackbar_notes_deleted_from_server, successCount)
                 successCount == 0 -> getString(R.string.snackbar_server_delete_failed)
@@ -517,7 +518,11 @@ class MainViewModel(application: Application) : AndroidViewModel(application) {
                     successCount + failCount
                 )
             }
-            _showToast.emit(message)
+            if (failCount > 0) {
+                SyncStateManager.showError(message)
+            } else {
+                SyncStateManager.showInfo(message)
+            }
         }
     }
     

android/app/src/main/java/dev/dettmer/simplenotes/ui/main/components/SyncProgressBanner.kt

@@ -15,6 +15,7 @@ import androidx.compose.foundation.layout.size
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.CheckCircle
 import androidx.compose.material.icons.filled.ErrorOutline
+import androidx.compose.material.icons.outlined.Info
 import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.Icon
 import androidx.compose.material3.LinearProgressIndicator
@@ -51,11 +52,13 @@ fun SyncProgressBanner(
     // Farbe animiert wechseln je nach State
     val isError = progress.phase == SyncPhase.ERROR
     val isCompleted = progress.phase == SyncPhase.COMPLETED
-    val isResult = isError || isCompleted
+    val isInfo = progress.phase == SyncPhase.INFO  // 🆕 v1.8.1 (IMPL_12)
+    val isResult = isError || isCompleted || isInfo
     
     val backgroundColor by animateColorAsState(
         targetValue = when {
             isError -> MaterialTheme.colorScheme.errorContainer
+            isInfo -> MaterialTheme.colorScheme.secondaryContainer  // 🆕 v1.8.1 (IMPL_12)
             else -> MaterialTheme.colorScheme.primaryContainer
         },
         label = "bannerColor"
@@ -64,6 +67,7 @@ fun SyncProgressBanner(
     val contentColor by animateColorAsState(
         targetValue = when {
             isError -> MaterialTheme.colorScheme.onErrorContainer
+            isInfo -> MaterialTheme.colorScheme.onSecondaryContainer  // 🆕 v1.8.1 (IMPL_12)
             else -> MaterialTheme.colorScheme.onPrimaryContainer
         },
         label = "bannerContentColor"
@@ -89,7 +93,7 @@ fun SyncProgressBanner(
                     verticalAlignment = Alignment.CenterVertically,
                     horizontalArrangement = Arrangement.spacedBy(10.dp)
                 ) {
-                    // Icon: Spinner (aktiv), Checkmark (completed), Error (error)
+                    // Icon: Spinner (aktiv), Checkmark (completed), Error (error), Info (info)
                     when {
                         isCompleted -> {
                             Icon(
@@ -99,6 +103,14 @@ fun SyncProgressBanner(
                                 tint = contentColor
                             )
                         }
+                        isInfo -> {  // 🆕 v1.8.1 (IMPL_12)
+                            Icon(
+                                imageVector = Icons.Outlined.Info,
+                                contentDescription = null,
+                                modifier = Modifier.size(18.dp),
+                                tint = contentColor
+                            )
+                        }
                         isError -> {
                             Icon(
                                 imageVector = Icons.Filled.ErrorOutline,
@@ -187,5 +199,6 @@ private fun phaseToString(phase: SyncPhase): String {
         SyncPhase.IMPORTING_MARKDOWN -> stringResource(R.string.sync_phase_importing_markdown)
         SyncPhase.COMPLETED -> stringResource(R.string.sync_phase_completed)
         SyncPhase.ERROR -> stringResource(R.string.sync_phase_error)
+        SyncPhase.INFO -> ""  // 🆕 v1.8.1 (IMPL_12): INFO nutzt immer resultMessage
     }
 }