Add A/B testing toggles to OCR Kombi Grid Review

Quality step toggles in admin-lehrer StepGridReview (port 3002):
- CLAHE checkbox (Step 3: image enhancement)
- MaxCol dropdown (Step 2: column limit, 0=off)
- MinConf dropdown (Step 1: OCR confidence, 0=auto)

Parameters flow through: StepGridReview → useGridEditor → build-grid
endpoint → _build_grid_core. MinConf filters words before grid building.

Toggle settings, click "Neu berechnen" to test each step individually.

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

admin-lehrer/components/grid-editor/useGridEditor.ts

@@ -28,6 +28,11 @@ export function useGridEditor(sessionId: string | null) {
   const [ipaMode, setIpaMode] = useState<IpaMode>('auto')
   const [syllableMode, setSyllableMode] = useState<SyllableMode>('auto')
 
+  // OCR Quality Steps (A/B testing toggles)
+  const [ocrEnhance, setOcrEnhance] = useState(true)
+  const [ocrMaxCols, setOcrMaxCols] = useState(0) // 0 = unlimited (admin pipeline default)
+  const [ocrMinConf, setOcrMinConf] = useState(0) // 0 = auto from quality score
+
   // Undo/redo stacks store serialized zone arrays
   const undoStack = useRef<string[]>([])
   const redoStack = useRef<string[]>([])
@@ -52,6 +57,9 @@ export function useGridEditor(sessionId: string | null) {
       const params = new URLSearchParams()
       params.set('ipa_mode', ipaMode)
       params.set('syllable_mode', syllableMode)
+      params.set('enhance', String(ocrEnhance))
+      if (ocrMaxCols > 0) params.set('max_cols', String(ocrMaxCols))
+      if (ocrMinConf > 0) params.set('min_conf', String(ocrMinConf))
       const res = await fetch(
         `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/build-grid?${params}`,
         { method: 'POST' },
@@ -70,7 +78,7 @@ export function useGridEditor(sessionId: string | null) {
     } finally {
       setLoading(false)
     }
-  }, [sessionId, ipaMode, syllableMode])
+  }, [sessionId, ipaMode, syllableMode, ocrEnhance, ocrMaxCols, ocrMinConf])
 
   const loadGrid = useCallback(async () => {
     if (!sessionId) return
@@ -85,6 +93,9 @@ export function useGridEditor(sessionId: string | null) {
         const params = new URLSearchParams()
         params.set('ipa_mode', ipaMode)
         params.set('syllable_mode', syllableMode)
+        params.set('enhance', String(ocrEnhance))
+        if (ocrMaxCols > 0) params.set('max_cols', String(ocrMaxCols))
+        if (ocrMinConf > 0) params.set('min_conf', String(ocrMinConf))
         const buildRes = await fetch(
           `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/build-grid?${params}`,
           { method: 'POST' },
@@ -981,5 +992,11 @@ export function useGridEditor(sessionId: string | null) {
     setIpaMode,
     syllableMode,
     setSyllableMode,
+    ocrEnhance,
+    setOcrEnhance,
+    ocrMaxCols,
+    setOcrMaxCols,
+    ocrMinConf,
+    setOcrMinConf,
   }
 }