Major improvements: Firebase data migration, enhanced loading screens, multi-day prayer tracking

- Migrated all localStorage data to Firebase for cross-device sync
  - Prayer drafts now stored in users/{userId}/drafts
  - Reminder settings in users/{userId}/settings
  - Prayer statistics in users/{userId}/statistics
- Implemented persistent 'most prayed for' tracking in Firebase
- Enhanced loading screen with animated backgrounds and gradients
- Fixed auth session restoration on hard refresh
- Added prayedDates array for multi-day prayer tracking
- Calendar now accurately shows all days a prayer was prayed for
- Enabled Firestore offline persistence for offline-first experience
- Updated Firestore security rules for new data structure
- Improved clock display (removed leading zero from hours)
- Moved clock below date on homepage with appropriate sizing
- Fixed data loading race conditions between auth and Firestore

firestore.rules

@@ -4,6 +4,21 @@ service cloud.firestore {
     // Allow authenticated users to read/write their own data
     match /users/{userId} {
       allow read, write: if request.auth != null && request.auth.uid == userId;
+      
+      // Allow users to read/write their own statistics
+      match /statistics/{document=**} {
+        allow read, write: if request.auth != null && request.auth.uid == userId;
+      }
+      
+      // Allow users to read/write their own settings
+      match /settings/{document=**} {
+        allow read, write: if request.auth != null && request.auth.uid == userId;
+      }
+      
+      // Allow users to read/write their own drafts
+      match /drafts/{document=**} {
+        allow read, write: if request.auth != null && request.auth.uid == userId;
+      }
     }
 
     // Allow public reading of answered prayers for testimony wall