fix: CRITICAL - remove double rotation (frontend + backend)

Root cause: Image was being rotated TWICE:
1. Frontend rotated it in the modal and sent processed blob
2. Backend rotated it AGAIN based on rotation_degrees

This double rotation made the image appear unrotated or distorted.

Solution: Remove frontend image processing entirely.
- Modal now sends ONLY the rotation value
- No imageBlob from modal (uses original)
- Backend receives original image + rotation value
- Backend applies rotation ONCE

Now image is rotated correctly by backend without duplication.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/components/AIOnboarding.tsx

@@ -96,9 +96,12 @@ export default function AIOnboarding({ onCancel, onComplete, categories, invento
       // CRITICAL: Update state AND processed blob BEFORE calling hook
       setExtractedItems(updatedItems);
 
+      // DON'T replace image blob - modal no longer processes image
+      // Backend will apply rotation to original image
       if (adjustments.imageBlob) {
-        console.log('[Update] Setting extractedImageBlob to processed blob:', adjustments.imageBlob.size, 'bytes');
-        setExtractedImageBlob(adjustments.imageBlob);
+        console.log('[Update] Processed blob received but NOT using (backend will process)');
+      } else {
+        console.log('[Update] No imageBlob - using original, backend will apply rotation');
       }
 
       // CRITICAL: Call hook with UPDATED item, not old one