feat(android): consolidate databases and add prefetch scheduling

Consolidate Java and Kotlin database implementations into unified
schema, add delayed prefetch scheduling, and fix notification
delivery issues.

Database Consolidation:
- Merge Java DailyNotificationDatabase into Kotlin DatabaseSchema
- Add migration path from v1 to v2 unified schema
- Include all entities: ContentCache, Schedule, Callback, History,
  NotificationContentEntity, NotificationDeliveryEntity,
  NotificationConfigEntity
- Add @JvmStatic getInstance() for Java interoperability
- Update DailyNotificationWorker and DailyNotificationStorageRoom
  to use unified database

Prefetch Functionality:
- Add scheduleDelayedFetch() to FetchWorker for 5-minute prefetch
  before notifications
- Support delayed WorkManager scheduling with initialDelay
- Update scheduleDailyNotification() to optionally schedule prefetch
  when URL is provided

Notification Delivery Fixes:
- Register NotifyReceiver in AndroidManifest.xml (was missing,
  causing notifications not to fire)
- Add safe database initialization with lazy getDatabase() helper
- Prevent PluginLoadException on database init failure

Build Configuration:
- Add kotlin-android and kotlin-kapt plugins
- Configure Room annotation processor (kapt) for Kotlin
- Add Room KTX dependency for coroutines support
- Fix Gradle settings with pluginManagement blocks

Plugin Methods Added:
- checkPermissionStatus() - detailed permission status
- requestNotificationPermissions() - request POST_NOTIFICATIONS
- scheduleDailyNotification() - schedule with AlarmManager
- configureNativeFetcher() - configure native content fetcher
- Various status and configuration methods

Code Cleanup:
- Remove duplicate BootReceiver.java (keep Kotlin version)
- Remove duplicate DailyNotificationPlugin.java (keep Kotlin version)
- Remove old Java database implementation
- Add native fetcher SPI registry (@JvmStatic methods)

The unified database ensures schedule persistence across reboots
and provides a single source of truth for all plugin data.
Prefetch scheduling enables content caching before notifications
fire, improving offline-first reliability.

test-apps/android-test-app/app/src/main/AndroidManifest.xml

@@ -34,6 +34,13 @@
                 <action android:name="com.timesafari.daily.NOTIFICATION" />
             </intent-filter>
         </receiver>
+        
+        <!-- NotifyReceiver for AlarmManager-based notifications -->
+        <receiver
+            android:name="com.timesafari.dailynotification.NotifyReceiver"
+            android:enabled="true"
+            android:exported="false">
+        </receiver>
             
         <receiver
             android:name="com.timesafari.dailynotification.BootReceiver"