fix(background): make wallpaper refresh reliable

[libhide]

Summary

• replace the two-hour onboarding schedule with a daily refresh around 7 AM
• move WorkManager scheduling out of Compose and migrate existing schedules once
• require network connectivity and use explicit exponential retry backoff
• preserve coroutine cancellation and retry transient worker failures
• honor automatic wallpaper setting during background refreshes
• continue posting the rich wallpaper notification after refresh
• observe persisted photo changes so an open Home screen updates after worker runs
• update WorkManager to 2.11.2

Verification

• ./gradlew clean :app:assembleDebug spotlessCheck :app:lintDebug --warning-mode all
• installed the debug APK on the API 36 emulator
• verified the migrated JobScheduler entry has a connected-network constraint and targets the next 7 AM
• verified subsequent scheduling uses the versioned update path