More Reliable Sync, Cleaner Menus, and Safer File Cleanup

🔄 Improvements

• Improved default branch adding behavior with a more consistent double-key method
• Cleaned up the menubar by removing unused buttons

🛠 Fixes

• Fixed: Undo now correctly restores deleted branch trees without losing child branches Demo video
• Fixed: Electron file sync no longer repeatedly uploads unchanged server files
• Fixed: Icon search now closes the context menu first, avoiding UI glitches

And other improvements