fix(ocr-pipeline): manual editor layout + no re-detection on cached result

- ManualColumnEditor now uses grid-cols-2 layout (image left, controls right)
  matching the normal view size so the image doesn't zoom in
- StepColumnDetection only runs auto-detection when no cached result exists;
  revisiting step 3 loads cached columns without re-running detection

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

admin-lehrer/components/ocr-pipeline/StepColumnDetection.tsx

@@ -20,15 +20,12 @@ export function StepColumnDetection({ sessionId, onNext }: StepColumnDetectionPr
   const [applying, setApplying] = useState(false)
   const [imageDimensions, setImageDimensions] = useState<{ width: number; height: number } | null>(null)
 
-  // Auto-trigger column detection on mount
+  // Fetch session info (image dimensions) + check for cached column result
   useEffect(() => {
-    if (!sessionId || columnResult) return
+    if (!sessionId || imageDimensions) return
 
-    const runDetection = async () => {
-      setDetecting(true)
-      setError(null)
+    const fetchSessionInfo = async () => {
       try {
-        // First check if columns already detected (reload case)
         const infoRes = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}`)
         if (infoRes.ok) {
           const info = await infoRes.json()
@@ -37,32 +34,22 @@ export function StepColumnDetection({ sessionId, onNext }: StepColumnDetectionPr
           }
           if (info.column_result) {
             setColumnResult(info.column_result)
-            setDetecting(false)
             return
           }
         }
-
-        // Run detection
-        const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/columns`, {
-          method: 'POST',
-        })
-        if (!res.ok) {
-          const err = await res.json().catch(() => ({ detail: res.statusText }))
-          throw new Error(err.detail || 'Spaltenerkennung fehlgeschlagen')
-        }
-        const data: ColumnResult = await res.json()
-        setColumnResult(data)
       } catch (e) {
-        setError(e instanceof Error ? e.message : 'Unbekannter Fehler')
-      } finally {
-        setDetecting(false)
+        console.error('Failed to fetch session info:', e)
       }
+
+      // No cached result - run auto-detection
+      runAutoDetection()
     }
 
-    runDetection()
-  }, [sessionId, columnResult])
+    fetchSessionInfo()
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [sessionId])
 
-  const handleRerun = useCallback(async () => {
+  const runAutoDetection = useCallback(async () => {
     if (!sessionId) return
     setDetecting(true)
     setError(null)
@@ -70,16 +57,23 @@ export function StepColumnDetection({ sessionId, onNext }: StepColumnDetectionPr
       const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/columns`, {
         method: 'POST',
       })
-      if (!res.ok) throw new Error('Spaltenerkennung fehlgeschlagen')
+      if (!res.ok) {
+        const err = await res.json().catch(() => ({ detail: res.statusText }))
+        throw new Error(err.detail || 'Spaltenerkennung fehlgeschlagen')
+      }
       const data: ColumnResult = await res.json()
       setColumnResult(data)
     } catch (e) {
-      setError(e instanceof Error ? e.message : 'Fehler')
+      setError(e instanceof Error ? e.message : 'Unbekannter Fehler')
     } finally {
       setDetecting(false)
     }
   }, [sessionId])
 
+  const handleRerun = useCallback(() => {
+    runAutoDetection()
+  }, [runAutoDetection])
+
   const handleGroundTruth = useCallback(async (gt: ColumnGroundTruth) => {
     if (!sessionId) return
     try {