feat(phase2): add admin photo replacement button with ItemDetailModal

- Add ItemDetailModal component for viewing item details and replacing photos
- Add photo replacement/deletion endpoints to API layer (PUT/DELETE /items/{id}/photo)
- Update InventoryTable to open detail modal on item click
- Show current photo thumbnail with Replace/Delete buttons
- Support uploading new photo with ItemPhotoUpload component
- Delete old photo on backend when replacing (no orphaned files)
- Full test coverage: 18 tests for ItemDetailModal component
- All 393 tests passing, zero TypeScript errors
- Build verified successfully

frontend/components/InventoryTable.tsx

@@ -5,6 +5,7 @@ import { Item } from '@/lib/db';
 import { ChevronRight, ChevronDown, Layers, Package } from 'lucide-react';
 import { clsx, type ClassValue } from 'clsx';
 import { twMerge } from 'tailwind-merge';
+import ItemDetailModal from '@/components/ItemDetailModal';
 
 function cn(...inputs: ClassValue[]) {
   return twMerge(clsx(inputs));
@@ -29,6 +30,22 @@ export default function InventoryTable({
   onEditCategory,
   categoriesList = []
 }: InventoryTableProps) {
+  const [selectedItemDetail, setSelectedItemDetail] = useState<Item | null>(null);
+  const [refreshTrigger, setRefreshTrigger] = useState(0);
+
+  const handleItemClick = (item: Item) => {
+    setSelectedItemDetail(item);
+    onItemClick(item);
+  };
+
+  const handleCloseDetail = () => {
+    setSelectedItemDetail(null);
+  };
+
+  const handleItemRefresh = () => {
+    setRefreshTrigger(prev => prev + 1);
+  };
+
   if (categories.length === 0) {
     return (
       <div className="py-20 text-center text-secondary">
@@ -81,7 +98,7 @@ export default function InventoryTable({
                 {categoryItems.map(item => (
                   <div
                     key={item.id}
-                    onClick={() => onItemClick(item)}
+                    onClick={() => handleItemClick(item)}
                     className="bg-background/40 border border-slate-800/50 p-4 rounded-2xl flex items-center justify-between hover:border-primary/40 cursor-pointer transition-all active:scale-[0.98]"
                   >
                     <div className="flex items-center gap-3 flex-1 min-w-0 pr-4">
@@ -109,6 +126,14 @@ export default function InventoryTable({
           </div>
         );
       })}
+
+      {selectedItemDetail && (
+        <ItemDetailModal
+          item={selectedItemDetail}
+          onClose={handleCloseDetail}
+          onItemRefresh={handleItemRefresh}
+        />
+      )}
     </section>
   );
 }