feat(editor): add tab strip with unsaved-close flow and refine sidebar/window controls
Add open-file tab strip below toolbar with tab selection and close buttons
- Track per-tab dirty state in TabData (
isDirty) - Mark tabs dirty on content change and clear dirty flag on successful save/save as
- Add close-confirmation dialog for unsaved tabs:
- Save
- Don't Save
- Cancel
Implement close helpers in ContentView actions:
- requestCloseTab
- saveAndClosePendingTab
- discardAndClosePendingTab
- Keep tab open when Save As is cancelled
- Fix left sidebar toolbar icon to always use left-sidebar symbol
- Keep right sidebar toggle separate and unchanged
- Continue using blank-window toolbar action for new windows`
Full Changelog: v0.3.1-alpha...v0.3.2-alpha