feat(ocr): Add docTR OCR engine with metrics infrastructure

Add docTR as primary OCR engine with 2-tier sequential processing,
OCR metrics tracking, and simplified engine selection.

Features:
- docTR OCR engine with light+medium preprocessing tiers
- doctr_plus mode with early exit optimization (~65% fast path)
- OCR metrics dashboard with per-engine statistics
- User OCR preference persistence
- Parallel worker pool for OCR processing
- Cross-validation for extraction quality

Engine options: tesseract, doctr, doctr_plus (recommended), paddleocr

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/config/menu.js

@@ -19,7 +19,8 @@ export const menuSections = [
     title: 'Sistem',
     items: [
       { to: '/reports/telegram', icon: 'pi pi-telegram', label: 'Telegram Bot' },
-      { to: '/reports/cache-stats', icon: 'pi pi-chart-bar', label: 'Statistici Cache' }
+      { to: '/reports/cache-stats', icon: 'pi pi-chart-bar', label: 'Statistici Cache' },
+      { to: '/data-entry/ocr-metrics', icon: 'pi pi-eye', label: 'Statistici OCR' }
     ]
   }
 ]