feat: refactor dual-track architecture (Phase 1-5)

## Backend Changes
- **Service Layer Refactoring**:
  - Add ProcessingOrchestrator for unified document processing
  - Add PDFTableRenderer for table rendering extraction
  - Add PDFFontManager for font management with CJK support
  - Add MemoryPolicyEngine (73% code reduction from MemoryGuard)

- **Bug Fixes**:
  - Fix Direct Track table row span calculation
  - Fix OCR Track image path handling
  - Add cell_boxes coordinate validation
  - Filter out small decorative images
  - Add covering image detection

## Frontend Changes
- **State Management**:
  - Add TaskStore for centralized task state management
  - Add localStorage persistence for recent tasks
  - Add processing state tracking

- **Type Consolidation**:
  - Merge shared types from api.ts to apiV2.ts
  - Update imports in authStore, uploadStore, ResultsTable, SettingsPage

- **Page Integration**:
  - Integrate TaskStore in ProcessingPage and TaskDetailPage
  - Update useTaskValidation hook with cache sync

## Testing
- Direct Track: edit.pdf (3 pages, 1.281s), edit3.pdf (2 pages, 0.203s)
- Cell boxes validation: 43 valid, 0 invalid
- Table merging: 12 merged cells verified

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/pages/SettingsPage.tsx

@@ -5,7 +5,7 @@ import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { Button } from '@/components/ui/button'
 import { useToast } from '@/components/ui/toast'
 import { apiClient } from '@/services/api'
-import type { ExportRule } from '@/types/api'
+import type { ExportRule } from '@/types/apiV2'
 
 export default function SettingsPage() {
   const { t } = useTranslation()