feat: Add interactive Table of Contents navigation with i18n support
Implements complete TOC feature for document navigation with bilingual support.
## TOC Detection & Extraction
- Pattern-based TOC detection with 3 regex patterns
- Heuristic validation (30%+ match ratio, 5+ entries, sequential pages)
- Hierarchical section key parsing (e.g., "4.1.2" → level 3, parent "4.1")
- Database schema with parent-child relationships
- Automatic extraction during OCR post-processing
- Server-side LRU caching (200 entries, 30min TTL)
## UI Components
- TocSidebar: Collapsible sidebar (320px) with auto-open on TOC presence
- TocEntry: Recursive component for hierarchical rendering
- Flex layout: Sidebar + PDF viewer side-by-side
- Active page highlighting with real-time sync
- localStorage persistence for sidebar state
## Navigation Features
- Click TOC entry → PDF jumps to page
- Deep link support: URL hash format #p=12
- Page change events: navidocs:pagechange custom event
- URL hash updates on all navigation (next/prev/goTo/TOC)
- Hash change listener for external navigation
- Page clamping and validation
## Search Integration
- "Jump to section" button in search results
- Shows when result has section field
- Navigates to document with page number and hash
## Accessibility
- ARIA attributes: role, aria-label, aria-expanded, aria-current
- Keyboard navigation: Enter/Space on entries, Tab focus
- Screen reader support with aria-live regions
- Semantic HTML with proper list/listitem roles
## Internationalization (i18n)
- Vue I18n integration with vue-i18n package
- English and French translations
- 8 TOC-specific translation keys
- Language switcher component in document viewer
- Locale persistence in localStorage
## Error Handling
- Specific error messages for each failure case
- Validation before processing (doc exists, has pages, has OCR)
- Non-blocking TOC extraction (doesn't fail OCR jobs)
- Detailed error returns: {success, error, entriesCount, pages}
## API Endpoints
- GET /api/documents/:id/toc?format=flat|tree
- POST /api/documents/:id/toc/extract
- Cache invalidation on re-extraction
## Testing
- Smoke test script: 9 comprehensive tests
- E2E testing guide with 5 manual scenarios
- Tests cover: API, caching, validation, navigation, search
## Database
- Migration 002: document_toc table
- Fields: id, document_id, title, section_key, page_start, level, parent_id, order_index
- Foreign keys with CASCADE delete
## Files Changed
- New: TocSidebar.vue, TocEntry.vue, LanguageSwitcher.vue
- New: toc-extractor.js, toc.js routes, i18n setup
- Modified: DocumentView.vue (sidebar, deep links, events)
- Modified: SearchView.vue (Jump to section button)
- Modified: ocr-worker.js (TOC post-processing)
- New: toc-smoke-test.sh, TOC_E2E_TEST.md
Generated with Claude Code (https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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