Add Box-Grid-Review step (Step 11) to OCR pipeline

New pipeline step between Gutter Repair and Ground Truth that processes
embedded boxes (grammar tips, exercises) independently from the main grid.

Backend:
- cv_box_layout.py: classify_box_layout() detects flowing/columnar/
  bullet_list/header_only layout types per box
- build_box_zone_grid(): layout-aware grid building (single-column for
  flowing text, independent columns for tabular content)
- POST /sessions/{id}/build-box-grids endpoint with SmartSpellChecker
- Layout type overridable per box via request body

Frontend:
- StepBoxGridReview.tsx: shows each box with cropped image + editable
  GridTable. Layout type dropdown per box. Auto-builds on first load.
- Auto-skip when no boxes detected on page
- Pipeline steps updated: 13 steps (0-12), Ground Truth moved to 12

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

admin-lehrer/app/(admin)/ai/ocr-kombi/page.tsx

@@ -16,6 +16,7 @@ import { StepStructure } from '@/components/ocr-kombi/StepStructure'
 import { StepGridBuild } from '@/components/ocr-kombi/StepGridBuild'
 import { StepGridReview } from '@/components/ocr-kombi/StepGridReview'
 import { StepGutterRepair } from '@/components/ocr-kombi/StepGutterRepair'
+import { StepBoxGridReview } from '@/components/ocr-kombi/StepBoxGridReview'
 import { StepGroundTruth } from '@/components/ocr-kombi/StepGroundTruth'
 import { useKombiPipeline } from './useKombiPipeline'
 
@@ -97,6 +98,8 @@ function OcrKombiContent() {
       case 10:
         return <StepGutterRepair sessionId={sessionId} onNext={handleNext} />
       case 11:
+        return <StepBoxGridReview sessionId={sessionId} onNext={handleNext} />
+      case 12:
         return (
           <StepGroundTruth
             sessionId={sessionId}

admin-lehrer/app/(admin)/ai/ocr-kombi/types.ts

@@ -40,6 +40,7 @@ export const KOMBI_V2_STEPS: PipelineStep[] = [
   { id: 'grid-build',    name: 'Grid-Aufbau',        icon: '🧱', status: 'pending' },
   { id: 'grid-review',   name: 'Grid-Review',        icon: '📊', status: 'pending' },
   { id: 'gutter-repair', name: 'Wortkorrektur',      icon: '🩹', status: 'pending' },
+  { id: 'box-review',    name: 'Box-Review',          icon: '📦', status: 'pending' },
   { id: 'ground-truth',  name: 'Ground Truth',       icon: '✅', status: 'pending' },
 ]
 
@@ -56,7 +57,8 @@ export const KOMBI_V2_UI_TO_DB: Record<number, number> = {
   8: 10,  // grid-build
   9: 11,  // grid-review
   10: 11, // gutter-repair (shares DB step with grid-review)
-  11: 12, // ground-truth
+  11: 11, // box-review (shares DB step with grid-review)
+  12: 12, // ground-truth
 }
 
 /** Map from DB step to Kombi V2 UI step index */
@@ -70,7 +72,7 @@ export function dbStepToKombiV2Ui(dbStep: number): number {
   if (dbStep === 9) return 7  // structure
   if (dbStep === 10) return 8 // grid-build
   if (dbStep === 11) return 9 // grid-review
-  return 11                   // ground-truth
+  return 12                   // ground-truth
 }
 
 /** Document group: groups multiple sessions from a multi-page upload */