feat(extension): add command bar popup with tag, note, search
Add a simple command bar popup to the browser extension with three
basic commands:
- tag: Add tags to the current page (comma-separated)
- note: Save a text note about the current page
- search: Search saved items by title, URL, or content
The popup UI follows the same patterns as the desktop cmd panel:
- Dark/light mode support via prefers-color-scheme
- Keyboard navigation (arrows, tab, enter, escape)
- Results list with icons and descriptions
Backend handlers in background.js:
- handleSaveTags: Creates/updates URL item and applies tags
- handleSaveNote: Creates text item with optional source URL metadata
- handleSearchItems: Filters items by title/content/URL match