refactor: Crop nach Deskew/Dewarp verschieben + content-basierter Buchscan-Crop

Pipeline-Reihenfolge neu: Orientierung → Begradigung → Entzerrung → Zuschneiden → Spalten...
Crop arbeitet jetzt auf dem bereits geraden Bild, was bessere Ergebnisse liefert.

page_crop.py komplett ersetzt: Adaptive Threshold + 4-Kanten-Erkennung
(Buchruecken-Schatten links, Ink-Projektion fuer alle Raender) statt
Otsu + groesste Kontur.

Backend: Step-Nummern, Input-Bilder, Reprocess-Kaskade angepasst.
Frontend: PIPELINE_STEPS umgeordnet, Switch-Cases, Vorher-Bilder aktualisiert.

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

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

@@ -71,8 +71,8 @@ export default function OcrPipelinePage() {
 
       // Determine which step to jump to based on current_step
       const dbStep = data.current_step || 1
-      // Steps: 1=deskew, 2=dewarp, 3=columns, ...
-      // UI steps are 0-indexed: 0=deskew, 1=dewarp, 2=columns, ...
+      // DB steps: 1=start, 2=orientation, 3=deskew, 4=dewarp, 5=crop, 6=columns, ...
+      // UI steps are 0-indexed: 0=orientation, 1=deskew, 2=dewarp, 3=crop, 4=columns, ...
       const uiStep = Math.max(0, dbStep - 1)
       const skipSteps = savedDocType?.skip_steps || []
 
@@ -205,8 +205,8 @@ export default function OcrPipelinePage() {
     handleNext()
   }
 
-  const handleDewarpNext = async () => {
-    // Auto-detect document type after dewarp, then advance
+  const handleCropNext = async () => {
+    // Auto-detect document type after crop (last image-processing step), then advance
     if (sessionId) {
       try {
         const res = await fetch(
@@ -273,9 +273,9 @@ export default function OcrPipelinePage() {
 
   const stepNames: Record<number, string> = {
     1: 'Orientierung',
-    2: 'Zuschneiden',
-    3: 'Begradigung',
-    4: 'Entzerrung',
+    2: 'Begradigung',
+    3: 'Entzerrung',
+    4: 'Zuschneiden',
     5: 'Spalten',
     6: 'Zeilen',
     7: 'Woerter',
@@ -312,11 +312,11 @@ export default function OcrPipelinePage() {
       case 0:
         return <StepOrientation sessionId={sessionId} onNext={handleOrientationComplete} />
       case 1:
-        return <StepCrop sessionId={sessionId} onNext={handleNext} />
-      case 2:
         return <StepDeskew sessionId={sessionId} onNext={handleNext} />
+      case 2:
+        return <StepDewarp sessionId={sessionId} onNext={handleNext} />
       case 3:
-        return <StepDewarp sessionId={sessionId} onNext={handleDewarpNext} />
+        return <StepCrop sessionId={sessionId} onNext={handleCropNext} />
       case 4:
         return <StepColumnDetection sessionId={sessionId} onNext={handleNext} />
       case 5:

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

@@ -310,9 +310,9 @@ export const IMAGE_STYLES: { value: ImageStyle; label: string }[] = [
 
 export const PIPELINE_STEPS: PipelineStep[] = [
   { id: 'orientation', name: 'Orientierung', icon: '🔄', status: 'pending' },
-  { id: 'crop', name: 'Zuschneiden', icon: '✂️', status: 'pending' },
   { id: 'deskew', name: 'Begradigung', icon: '📐', status: 'pending' },
   { id: 'dewarp', name: 'Entzerrung', icon: '🔧', status: 'pending' },
+  { id: 'crop', name: 'Zuschneiden', icon: '✂️', status: 'pending' },
   { id: 'columns', name: 'Spalten', icon: '📊', status: 'pending' },
   { id: 'rows', name: 'Zeilen', icon: '📏', status: 'pending' },
   { id: 'words', name: 'Woerter', icon: '🔤', status: 'pending' },