* feat: add plan/build mode switching and Plan view tab
Add PlanView view and integrate plan tab into main layout
Introduce plan_enter and plan_exit tools with icons and status strings
Persist per-session agent selections in context to reduce UI flicker during mode switches
* feat: enchanced plan discovery checks in header and plan view
* fix(ui): align PlanView and Header with sessionDirectory logic
Remove dependency on context store in header and compute sessionDirectory from session or currentDirectory
Compute display and repo paths using sessionDirectory for PlanView and update path resolution
Poll plan content every 3 seconds to reflect changes without heavy retries
* feat(ui): improve header tab switching and add copy buttons for plan
Switch header tab navigation to central UI store and auto-switch when plan is unavailable
Show checkmark icon after copying file contents or path with auto-hide timeout
Extend plan view path resolution to prefer session directory when present
* feat: add Files tab for browsing workspace files
- Add Files tab between Diff and Terminal in header
- Implement hierarchical file tree with expand/collapse
- Add fuzzy search with debouncing and relevance ranking
- Support gitignore filtering via `git check-ignore` (web + desktop)
- Add syntax highlighting for 150+ file types
- Add image preview (SVG, PNG, JPG, etc.)
- Add line numbers, wrap toggle, and copy button
- Desktop: split-pane layout matching DiffView
- Mobile: drill-in navigation with full-width sidebar
- Update help dialog with Cmd+3 shortcut
- Increase header breakpoint to 940px for new tab
* feat: enhance context and session stores to track agent/model/variant choices for historical sessions
* feat: implement line selection and commenting functionality in FilesView
Bohdan Triapitsyn