* feat: added themes system
* feat: smart sidebar auto-hide for files/diff tabs + lower files sidebar threshold
* feat: added Checkbox component and update theming
- Add reusable Checkbox component for toggles across UI
- Replace several inputs with Checkbox in settings and commands panels
- Add DiffIcon and apply surface/border theming to key UI areas
* feat: Add convert-vscode-theme.cjs to convert VS Code themes to OpenChamber format
* refactor: remove unused permission logic from ChatInput
- Remove unused permission rules parsing logic from ChatInput
- Memoize renderTheme in DiffWorkerProvider to avoid unnecessary recalculations
- Remove forceOpaque helper in vscode theme adapter
* fix: guard VSCode theme loading in MarkdownRenderer
* feat: add custom user themes loading and reload
- Load user themes from ~/.config/openchamber/themes at runtime
- Expose /api/config/themes to fetch custom themes
- Allow theme reloading from Settings → Theme → Reload themes in the UI
* fix(ui): remove fixed sessions button and mac titlebar coupling
Remove fixed sessions button from header on desktop Mac
Eliminate Mac titlebar spacer and drag-to-dock logic in sidebar
Update layout to rely on standard header/sidebar without mac-specific tweaks
* feat: improve mobile header with session toggle and back button
Add back button in mobile header to exit session switcher
Show Sessions label when session switcher is open in mobile header
Toggle between opening sessions and back navigation based on session state
Add file management API and UI components
Implement directory listing, search and CRUD operations in desktop backend
Expose new Files API on frontend to list, search, and modify files