Consolidate extension data providers and add side effects catch-up

- Create unified ExtensionDataProvider for Widget and Watch targets
- Remove duplicate WatchDataProvider and WatchConnectivityManager from Watch App
- Add side effects catch-up mechanism in MoodLogger for widget votes
- Process pending side effects on app launch and midnight background task
- Reduce ~450 lines of duplicated code across targets

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Shared/BGTask.swift

@@ -20,6 +20,10 @@ class BGTask {
         }
 
         DataController.shared.fillInMissingDates()
+
+        // Catch up on any side effects from widget/watch votes
+        MoodLogger.shared.processPendingSideEffects()
+
         task.setTaskCompleted(success: true)
     }