- Enable contextIsolation, disable nodeIntegration, remove enableRemoteModule
- Add preload.js with safe contextBridge API exposure
- Fix OS command injection: exec() → execFile() in open-file-in-player
- Fix DOM XSS: replace innerHTML with textContent/createElement in FileListManager, UIManager, ModalManager
- Remove direct fs/electron access from renderer, route through IPC
- Add validate-folder and get-file-stats IPC handlers
- Load renderer modules via script tags with require polyfill
- Add double-click handler to make file names editable in UI
- Remove duplicate IPC handler for rename-file in renderer.js
- Fix checkEpisodeCountMatch to properly validate sequential episodes
- Fix begin-mapping to handle both season folder and show folder cases
- Improve open-file-in-player handler to properly log results
- Split renderer.js into 9 manager classes following SOLID principles:
* AppState - State management
* EpisodeManager - Episode numbering and range editing
* TagManager - File tagging system
* SearchManager - TheTVDB search integration
* FileManager - Directory and file operations
* ModalManager - Video preview modals
* ProgressManager - Progress display
* FileListManager - File list rendering and drag/drop
* UIManager - Main UI coordinator
- Add comprehensive test suite (test-renderer-classes-comprehensive.js)
with 100+ tests covering all business logic
- Fix drag/drop handler 'this' binding issues
- Add CSS for highlighted episodes and improved file list styling
- Restore all original functionality including episode cascading,
tagging system, TVDB search, and Jellyfin naming
