feat: Orientierungserkennung in OCR-Pipeline-Deskew integrieren

detect_and_fix_orientation() wird jetzt vor dem Deskew-Schritt in der
OCR-Pipeline ausgefuehrt, sodass 90/180/270°-gedrehte Scans automatisch
korrigiert werden. Frontend zeigt Orientierungskorrektur als Info-Banner.

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

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

@@ -85,6 +85,7 @@ export interface DeskewResult {
   angle_applied: number
   method_used: 'hough' | 'word_alignment' | 'manual' | 'iterative' | 'two_pass' | 'three_pass' | 'manual_combined'
   confidence: number
+  orientation_degrees?: number
   duration_seconds: number
   deskewed_image_url: string
   binarized_image_url: string

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

@@ -59,6 +59,11 @@ export function DeskewControls({
       {/* Results */}
       {deskewResult && (
         <div className="bg-white dark:bg-gray-800 rounded-lg border border-gray-200 dark:border-gray-700 p-4">
+          {deskewResult.orientation_degrees ? (
+            <div className="flex items-center gap-2 mb-2 px-2 py-1 bg-amber-50 dark:bg-amber-900/20 text-amber-700 dark:text-amber-400 rounded text-xs">
+              Seite wurde um {deskewResult.orientation_degrees}° gedreht (Orientierungskorrektur)
+            </div>
+          ) : null}
           <div className="flex flex-wrap items-center gap-3 text-sm">
             <div>
               <span className="text-gray-500">Winkel:</span>{' '}

klausur-service/backend/ocr_pipeline_api.py

@@ -54,6 +54,7 @@ from cv_vocab_pipeline import (
     deskew_image_by_word_alignment,
     deskew_image_iterative,
     deskew_two_pass,
+    detect_and_fix_orientation,
     detect_column_geometry,
     detect_document_type,
     detect_row_geometry,
@@ -475,6 +476,16 @@ async def auto_deskew(session_id: str):
 
     t0 = time.time()
 
+    # Orientation detection (fix 90/180/270° rotations from scanners)
+    img_bgr, orientation_deg = detect_and_fix_orientation(img_bgr)
+    if orientation_deg:
+        # Update original in cache + DB so all subsequent steps use corrected image
+        cached["original_bgr"] = img_bgr
+        success_ori, ori_buf = cv2.imencode(".png", img_bgr)
+        if success_ori:
+            await update_session_db(session_id, original_png=ori_buf.tobytes())
+        logger.info(f"OCR Pipeline: orientation corrected {orientation_deg}° for session {session_id}")
+
     # Two-pass deskew: iterative (±5°) + word-alignment residual check
     deskewed_bgr, angle_applied, two_pass_debug = deskew_two_pass(img_bgr.copy())
 
@@ -523,6 +534,7 @@ async def auto_deskew(session_id: str):
         "angle_residual": round(angle_residual, 3),
         "angle_textline": round(angle_textline, 3),
         "angle_applied": round(angle_applied, 3),
+        "orientation_degrees": orientation_deg,
         "method_used": method_used,
         "confidence": round(confidence, 2),
         "duration_seconds": round(duration, 2),
@@ -551,6 +563,7 @@ async def auto_deskew(session_id: str):
                 f"-> {method_used} total={angle_applied:.2f}")
 
     await _append_pipeline_log(session_id, "deskew", {
+        "orientation": orientation_deg,
         "angle_applied": round(angle_applied, 3),
         "angle_iterative": round(angle_iterative, 3),
         "angle_residual": round(angle_residual, 3),