feat: add image confirmation step to AI extraction flow

Users now see the extracted photo during item editing and can choose to:
- 'Use Photo': Auto-save the image with the item
- 'Skip Photo': Create item without saving the photo

Changes:
1. frontend/components/AIOnboarding.tsx: Added image preview panel in edit form
   - Shows extracted image to user
   - Buttons to accept/reject photo
   - Visual feedback when photo is skipped

2. frontend/hooks/useAIExtraction.ts: Updated confirmSingleItem and confirmAllItems
   - Respect user's photo decision (_skipPhoto flag)
   - Only pass extractedImageBlob if user approved it
   - Prevents unwanted auto-photo-save

This gives users full control over which extracted photos are auto-saved.

frontend/hooks/useAIExtraction.ts

@@ -133,6 +133,8 @@ export function useAIExtraction(inventory: Item[], onComplete: (itemData: any) =
 
   const confirmSingleItem = (index: number) => {
     const data = extractedItems[index];
+    const skipPhoto = data._skipPhoto === true; // User explicitly rejected the photo
+
     const newItem = {
       name: String(data.Item || data.name || "New AI Item"),
       category: String(data.Category || data.category || "Uncategorized"),
@@ -149,9 +151,11 @@ export function useAIExtraction(inventory: Item[], onComplete: (itemData: any) =
       min_quantity: 1.0,
       box_label: data.box_label ? String(data.box_label) : null,
       labels_data: JSON.stringify(data),
-      // Pass extracted image blob and image_processing metadata for auto-photo-save
-      extractedImageBlob,
-      imageProcessing: data.image_processing
+      // Only pass image blob if user approved it
+      ...(skipPhoto ? {} : {
+        extractedImageBlob,
+        imageProcessing: data.image_processing
+      })
     };
     onComplete(newItem);
 
@@ -174,6 +178,8 @@ export function useAIExtraction(inventory: Item[], onComplete: (itemData: any) =
     try {
       for (let i = 0; i < itemsToProcess.length; i++) {
         const data = itemsToProcess[i];
+        const skipPhoto = data._skipPhoto === true;
+
         const newItem = {
           name: String(data.Item || data.name || "New AI Item"),
           category: String(data.Category || data.category || "Uncategorized"),
@@ -190,9 +196,11 @@ export function useAIExtraction(inventory: Item[], onComplete: (itemData: any) =
           min_quantity: 1.0,
           box_label: data.box_label ? String(data.box_label) : null,
           labels_data: JSON.stringify(data),
-          // Pass extracted image blob and image_processing metadata for auto-photo-save
-          extractedImageBlob,
-          imageProcessing: data.image_processing
+          // Only pass image blob if user approved it
+          ...(skipPhoto ? {} : {
+            extractedImageBlob,
+            imageProcessing: data.image_processing
+          })
         };
         await onComplete(newItem);
       }