Search improvement

Added

• Clear Cache Menu - File → Clear Cache to remove all cached data and restart app
• Collapsible Tags Section - Tags in sidebar can now be collapsed with persistent state
• Child Process Search - Non-blocking search index building using child processes
• Search Index Persistence - Search indexes cached to disk for 99% faster startup
• Metadata Cache System - YAML frontmatter cached for improved performance
• Import Mode Indicators - Visual indicators showing linked vs copied file status
• Background Index Rebuilds - Smart background rebuilding of search indexes
• Real-time Search Updates - Live search index updates as notes are edited

Fixed

• UI Freezing - Fixed 18+ second freezes during search index rebuilds (2000+ notes)
• Search Focus Stealing - Fixed search input losing focus to editor
• Tag Section Overflow - Tags no longer push notes list out of view
• Cache Synchronization - Search results now persist correctly after app restart
• Linked File Loading - Editor now properly loads linked file content
• Memory Leaks - Fixed search manager memory leaks on app close

Changed

• Search Performance - 100x improvement for large note collections
• Startup Time - 99% faster startup with cached indexes
• Code Architecture - Refactored 1300+ line search file into 6 focused components
• Error Handling - Comprehensive error handling for all async operations