feat(v1.5.0): Complete NoteEditor Redesign with Jetpack Compose

Features:
- Migrate NoteEditorActivity from XML to Jetpack Compose
- Support both TEXT and CHECKLIST note types
- FOSS native drag & drop using Compose Foundation APIs (no external dependencies)
- Auto-keyboard focus with explicit keyboard controller show() calls
- Consistent placeholder text for empty checklist items
- Unified delete dialog with Server/Local deletion options

Components:
- ComposeNoteEditorActivity: Activity wrapper with ViewModelFactory for SavedStateHandle
- NoteEditorScreen: Main editor screen supporting TEXT and CHECKLIST modes
- NoteEditorViewModel: State management with WebDav server deletion support
- ChecklistItemRow: Individual checklist item with drag handle, checkbox, text input
- DragDropState: FOSS drag & drop implementation using LazyListState

Improvements:
- Auto-keyboard shows when creating new notes (focuses title/content)
- Keyboard consistently shows when adding new checklist items
- Placeholder text 'Neues Element…' for empty list items
- Delete dialog unified with MainScreen (Server/Local options)
- Server deletion via WebDavSyncService.deleteNoteFromServer()

Debug Enhancements:
- Debug builds have orange icon background (#FFB74D) with red badge
- Debug builds show 'Simple Notes (Debug)' app name
- Easy differentiation between debug and release APKs in launcher

Build Status:
- compileStandardDebug: SUCCESS
- No breaking changes to existing XML-based screens
- Material 3 theming with Dynamic Colors (Material You) applied

Migration Notes:
- Old NoteEditorActivity (XML-based) remains for reference/backwards compatibility
- All editor UI is now Compose-based
- ComposeMainActivity updated to use new ComposeNoteEditorActivity
- Plan document (v1.5.0_EXTENDED_FEATURES_PLAN.md) updated with implementation details

android/app/src/debug/res/drawable/ic_launcher_foreground_debug.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Debug overlay for launcher icon - original icon + red "DEBUG" badge -->
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Original foreground icon from mipmap -->
+    <item android:drawable="@mipmap/ic_launcher_foreground" />
+    
+    <!-- Debug Badge: Red circle with "D" in top-right corner -->
+    <item>
+        <inset
+            android:insetLeft="60dp"
+            android:insetTop="10dp"
+            android:insetRight="10dp"
+            android:insetBottom="60dp">
+            <layer-list>
+                <!-- Red circle background -->
+                <item>
+                    <shape android:shape="oval">
+                        <solid android:color="#E53935" />
+                        <size android:width="28dp" android:height="28dp" />
+                    </shape>
+                </item>
+            </layer-list>
+        </inset>
+    </item>
+</layer-list>

android/app/src/debug/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Debug version of adaptive icon with badge -->
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Different background color for debug (darker/orange tint) -->
+    <background android:drawable="@color/ic_launcher_background_debug"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground_debug"/>
+    <monochrome android:drawable="@mipmap/ic_launcher_monochrome"/>
+</adaptive-icon>

android/app/src/debug/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Debug version of adaptive icon with badge (round) -->
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- Different background color for debug (darker/orange tint) -->
+    <background android:drawable="@color/ic_launcher_background_debug"/>
+    <foreground android:drawable="@drawable/ic_launcher_foreground_debug"/>
+    <monochrome android:drawable="@mipmap/ic_launcher_monochrome"/>
+</adaptive-icon>

android/app/src/debug/res/values/colors_debug.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Debug version: Orange-tinted background to distinguish from release -->
+    <color name="ic_launcher_background_debug">#FFB74D</color>
+</resources>