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/ocr-pipeline/StepGridReview.tsx

@@ -61,6 +61,12 @@ export function StepGridReview({ sessionId, onNext, saveRef }: StepGridReviewPro
     setIpaMode,
     syllableMode,
     setSyllableMode,
+    ocrEnhance,
+    setOcrEnhance,
+    ocrMaxCols,
+    setOcrMaxCols,
+    ocrMinConf,
+    setOcrMinConf,
   } = useGridEditor(sessionId)
 
   const [showImage, setShowImage] = useState(true)
@@ -256,6 +262,34 @@ export function StepGridReview({ sessionId, onNext, saveRef }: StepGridReviewPro
             Alle akzeptieren
           </button>
         )}
+        {/* OCR Quality Steps (A/B Testing) */}
+        <span className="text-gray-400 dark:text-gray-500">|</span>
+        <label className="flex items-center gap-1 cursor-pointer" title="Step 3: CLAHE + Bilateral-Filter Enhancement">
+          <input type="checkbox" checked={ocrEnhance} onChange={(e) => setOcrEnhance(e.target.checked)} className="rounded w-3 h-3" />
+          <span className="text-gray-500 dark:text-gray-400">CLAHE</span>
+        </label>
+        <label className="flex items-center gap-1" title="Step 2: Max Spaltenanzahl (0=unbegrenzt)">
+          <span className="text-gray-500 dark:text-gray-400">MaxCol:</span>
+          <select value={ocrMaxCols} onChange={(e) => setOcrMaxCols(Number(e.target.value))} className="px-1 py-0.5 text-xs rounded border border-gray-200 dark:border-gray-600 bg-white dark:bg-gray-700 text-gray-700 dark:text-gray-300">
+            <option value={0}>off</option>
+            <option value={2}>2</option>
+            <option value={3}>3</option>
+            <option value={4}>4</option>
+            <option value={5}>5</option>
+          </select>
+        </label>
+        <label className="flex items-center gap-1" title="Step 1: Min OCR Confidence (0=auto)">
+          <span className="text-gray-500 dark:text-gray-400">MinConf:</span>
+          <select value={ocrMinConf} onChange={(e) => setOcrMinConf(Number(e.target.value))} className="px-1 py-0.5 text-xs rounded border border-gray-200 dark:border-gray-600 bg-white dark:bg-gray-700 text-gray-700 dark:text-gray-300">
+            <option value={0}>auto</option>
+            <option value={20}>20</option>
+            <option value={30}>30</option>
+            <option value={40}>40</option>
+            <option value={50}>50</option>
+            <option value={60}>60</option>
+          </select>
+        </label>
+
         <div className="ml-auto flex items-center gap-2">
           <button
             onClick={() => {