v1.3.1 - Multi-Device Sync Fix + Performance + Restore Bug Fix

🔧 Fixed:
- Multi-device JSON sync now works (thanks Thomas!)
- Restore from Server skipped files (timestamp bug)
- No duplicate downloads
- First MD sync after export now fast

⚡ Performance:
- JSON sync: 12-14s → 2-3s
- Hybrid timestamp + E-Tag optimization
- Matches Markdown sync speed

✨ New:
- Sync status UI in MainActivity
- Content-based MD import
- Debug logging improvements
- SyncStateManager for sync coordination

🔧 Technical:
- Clear lastSyncTimestamp on restore
- Clear E-Tag caches on restore
- E-Tag refresh after upload
- Fixed timestamp update after MD export

fastlane/metadata/android/en-US/changelogs/9.txt

@@ -0,0 +1,13 @@
+v1.3.1 - Multi-Device Sync Fix + Performance
+
+🔧 Multi-Device JSON Sync (Thanks Thomas!):
+• JSON files now sync between devices
+• Works without Markdown enabled
+• No duplicate downloads anymore
+
+⚡ Performance Improvements:
+• Sync speed: 12-14s → 2-3s
+• First sync after MD export now fast
+• JSON matches Markdown speed
+
++ Sync status UI, content MD import, debug tools