feat: Konfigurierbare Sync-Intervalle + Über-Sektion (v1.1.0) (#1)

* feat: WiFi-Connect Auto-Sync + Debug Logging [skip ci]

- WiFi-Connect Auto-Sync via NetworkCallback + Broadcast (statt WorkManager)
- onResume Auto-Sync mit Toast-Feedback (nur Success)
- File-Logging Feature für Debugging (letzte 500 Einträge)
- Settings: Debug/Logs Section mit Test-Button
- FileProvider für Log-Sharing
- Extensive Debug-Logs für NetworkMonitor + MainActivity
- Material Design 3 Migration (alle 17 Tasks)
- Bug-Fixes: Input underlines, section rename, swipe-to-delete, flat cards

PROBLEM: WiFi-Connect sendet Broadcast aber MainActivity empfängt nicht
→ Benötigt logcat debugging auf anderem Gerät

* 🐛 fix: Remove WiFi-Connect related code and UI elements to streamline sync process

* feat: Konfigurierbare Sync-Intervalle + Über-Sektion (v1.1.0)

## Neue Features

### Konfigurierbare Sync-Intervalle
- Wählbare Intervalle: 15/30/60 Minuten in Settings
- Transparente Akkuverbrauchs-Anzeige (0.2-0.8% pro Tag)
- Sofortige Anwendung ohne App-Neustart
- NetworkMonitor liest Intervall dynamisch aus SharedPreferences

### Über-Sektion
- App-Version & Build-Datum Anzeige
- Klickbare Links zu GitHub Repository & Entwickler-Profil
- Lizenz-Information (MIT License)
- Ersetzt alte Debug/Logs Sektion

## Verbesserungen

- Benutzerfreundliche Doze-Mode Erklärung in Settings
- Keine störenden Sync-Fehler Toasts mehr im Hintergrund
- Modernisierte README mit Badges und kompakter Struktur
- F-Droid Metadaten aktualisiert (changelogs + descriptions)

## Technische Änderungen

- Version Bump: 1.0 → 1.1.0 (versionCode: 1 → 2)
- BUILD_DATE buildConfigField hinzugefügt
- PREF_SYNC_INTERVAL_MINUTES Konstante in Constants.kt
- NetworkMonitor.startPeriodicSync() nutzt konfigurierbare Intervalle
- SettingsActivity: setupSyncIntervalPicker() + setupAboutSection()
- activity_settings.xml: RadioGroup für Intervalle + About Cards

android/app/src/main/res/values/themes.xml

@@ -1,9 +1,45 @@
 <resources xmlns:tools="http://schemas.android.com/tools">
     <!-- Base application theme. -->
     <style name="Base.Theme.SimpleNotes" parent="Theme.Material3.DayNight.NoActionBar">
-        <!-- Customize your light theme here. -->
-        <!-- <item name="colorPrimary">@color/my_light_primary</item> -->
+        <!-- Material 3 Color System -->
+        <item name="colorPrimary">@color/md_theme_light_primary</item>
+        <item name="colorOnPrimary">@color/md_theme_light_onPrimary</item>
+        <item name="colorPrimaryContainer">@color/md_theme_light_primaryContainer</item>
+        <item name="colorOnPrimaryContainer">@color/md_theme_light_onPrimaryContainer</item>
+        
+        <item name="colorSecondary">@color/md_theme_light_secondary</item>
+        <item name="colorOnSecondary">@color/md_theme_light_onSecondary</item>
+        <item name="colorSecondaryContainer">@color/md_theme_light_secondaryContainer</item>
+        <item name="colorOnSecondaryContainer">@color/md_theme_light_onSecondaryContainer</item>
+        
+        <item name="colorTertiary">@color/md_theme_light_tertiary</item>
+        <item name="colorOnTertiary">@color/md_theme_light_onTertiary</item>
+        <item name="colorTertiaryContainer">@color/md_theme_light_tertiaryContainer</item>
+        <item name="colorOnTertiaryContainer">@color/md_theme_light_onTertiaryContainer</item>
+        
+        <item name="colorError">@color/md_theme_light_error</item>
+        <item name="colorOnError">@color/md_theme_light_onError</item>
+        <item name="colorErrorContainer">@color/md_theme_light_errorContainer</item>
+        <item name="colorOnErrorContainer">@color/md_theme_light_onErrorContainer</item>
+        
+        <item name="android:colorBackground">@color/md_theme_light_background</item>
+        <item name="colorOnBackground">@color/md_theme_light_onBackground</item>
+        <item name="colorSurface">@color/md_theme_light_surface</item>
+        <item name="colorOnSurface">@color/md_theme_light_onSurface</item>
+        <item name="colorSurfaceVariant">@color/md_theme_light_surfaceVariant</item>
+        <item name="colorOnSurfaceVariant">@color/md_theme_light_onSurfaceVariant</item>
+        
+        <item name="colorOutline">@color/md_theme_light_outline</item>
+        <item name="colorOutlineVariant">@color/md_theme_light_outlineVariant</item>
     </style>
 
     <style name="Theme.SimpleNotes" parent="Base.Theme.SimpleNotes" />
-</resources>
+    
+    <!-- Splash Screen Theme (Android 12+) -->
+    <style name="Theme.SimpleNotes.Splash" parent="Theme.SplashScreen">
+        <item name="windowSplashScreenBackground">?attr/colorPrimary</item>
+        <item name="windowSplashScreenAnimatedIcon">@drawable/ic_splash_icon</item>
+        <item name="windowSplashScreenAnimationDuration">500</item>
+        <item name="postSplashScreenTheme">@style/Theme.SimpleNotes</item>
+    </style>
+</resources>