feat: Template Browser Phase 5 - Interactive Enhancements (#98) (#106)

* feat: Template Browser Phase 5 - Interactive Enhancements (#98)

Implemented all five Phase 5 interactive enhancements:

1. **Keyboard Navigation**
   - `/` to focus search input
   - `ESC` to clear search or close modals
   - Arrow keys (↑↓) for card navigation with visual focus
   - `Enter` to create note from focused card
   - `Space` to toggle preview on focused card
   - `F` to toggle favorite on focused card
   - `?` to show/hide keyboard shortcuts hint panel

2. **Favorites System**
   - Star button (⭐/☆) on each template card
   - Click to toggle favorite status
   - Persisted in VS Code webview state
   - Filter templates by favorites (Show Only dropdown)
   - Visual indicator for favorited templates

3. **Context Menus**
   - Right-click on any template card
   - Context-aware menu items:
     * Create Note
     * Preview
     * Add/Remove Favorites
     * Edit (custom templates only)
     * Duplicate (custom templates only)
     * Export
     * Copy Template ID
     * Delete (custom templates only)
   - Separators for logical grouping
   - Auto-positioning to prevent off-screen menus

4. **Empty State Guidance**
   - Context-aware messaging for different scenarios:
     * No templates at all (with refresh action)
     * No favorites selected (with "Show All" action)
     * No search results (with clear search action)
     * No results with filters (with clear all filters action)
   - Actionable buttons for quick navigation
   - Helpful guidance text for each scenario

5. **Usage Tracking**
   - Automatically increment usage_count when creating from template
   - Update last_used timestamp with ISO date
   - Persists to JSON template files
   - Enables sorting by "Most Used"
   - Enables filtering by "Recently Used" (last 7 days)
   - Usage data displayed on template cards with trends

Technical improvements:
- Added Phase 5 CSS styles for favorites, context menus, keyboard focus
- Implemented keyboard shortcuts hint panel (bottom-right overlay)
- Enhanced event delegation for context menu items
- Added helper functions: isInputFocused(), navigateCards(), toggleKeyboardHint()
- Improved empty state rendering with getEmptyStateHtml()
- Updated template cards with tabindex and favorite buttons
- Context menu closes on click outside or ESC key

Closes #98

* Update src/templates/templateBrowserView.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* Update src/templates/templateBrowserView.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* fix: Address code review feedback for Phase 5

Fixed compilation errors and addressed code review suggestions:

1. **Fixed TypeScript compilation errors**:
   - Pre-escape templateId to avoid nested template literal issues
   - Changed "Copy Template ID" from onclick to data-command
   - Added copyTemplateId command handler

2. **Fixed defaultFilterState bug**:
   - Replaced spread of undefined variable with literal object
   - clearAllFilters() now works correctly

3. **Reduced code duplication**:
   - Added getFocusedCard() helper function
   - Refactored keyboard handlers to use the helper
   - Follows DRY principle

Changes address feedback from:
- Compilation error: Cannot find name 'escapeHtml'
- Compilation error: Cannot find name 'templateId'
- Code review: Duplicated logic in keydown handler
- Code review: clearAllFilters defaultFilterState bug

Note on remaining suggestions:
- Race condition warning acknowledged but low-priority for desktop app
- Keyboard shortcuts hardcoded intentionally for simplicity

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: 3 people