feat: OCR pipeline v2.1 – narrow column OCR, dewarp automation, Fabric.js editor

Proposal B: Adaptive padding, crop upscaling, PSM selection, row-strip re-OCR
for narrow columns (<15% width) – expected accuracy boost 60-70% → 85-90%.

Proposal A: New text-line straightness detector (Method D), quality gate
(rejects counterproductive corrections), 2-pass projection refinement,
higher confidence thresholds – expected manual dewarp reduction to <10%.

Proposal C: Fabric.js canvas editor with drag/drop, inline editing, undo/redo,
opacity slider, zoom, PDF/DOCX export endpoints.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-lehrer/package.json

@@ -27,6 +27,7 @@
     "react-dom": "^18.3.1",
     "reactflow": "^11.11.4",
     "recharts": "^2.15.0",
+    "fabric": "^6.0.0",
     "uuid": "^13.0.0"
   },
   "devDependencies": {