feat: add multi-select upload and unified selection bar on images page

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

src/hooks/useImages.ts

@@ -353,6 +353,16 @@ export function useImages() {
     }
   }, [items, uploadOne])
 
+  const uploadSelected = useCallback(async (ids: Set<string>) => {
+    const toUpload = items.filter(i =>
+      ids.has(i.id) && (i.status === 'ready' || i.status === 'converted') && !!i.shopifyProductId
+    )
+    for (const item of toUpload) {
+      await uploadOne(item.id)
+      await new Promise(r => setTimeout(r, 500))
+    }
+  }, [items, uploadOne])
+
   const removeItem = useCallback((id: string) => {
     dispatch({ type: 'REMOVE', id })
   }, [])
@@ -366,5 +376,5 @@ export function useImages() {
     [items, update],
   )
 
-  return { items, addFiles, setFeather, setAlphaThreshold, rotate, uploadOne, uploadAll, removeItem, assignProduct, reprocess, detour }
+  return { items, addFiles, setFeather, setAlphaThreshold, rotate, uploadOne, uploadAll, uploadSelected, removeItem, assignProduct, reprocess, detour }
 }