feat: frontend MVP — auth, timeline, upload, albums, admin, image viewer

Backend:
- user roles (DB + JWT + first-user-is-admin)
- volume-aware file resolver (multi-volume asset serving)
- directory scanner uses volume URI directly
- date-summary endpoint (capture date from EXIF)
- timeline ordered by capture date
- list endpoints: volumes, plugins, pipelines, library paths
- delete endpoints: volumes, library paths
- configurable upload body limit (MAX_UPLOAD_BYTES)

Frontend:
- auth: login/register, token refresh, role-based admin gate
- timeline: date-grouped grid, infinite scroll, date scrubber
- image viewer: fullscreen zoom/pan/pinch, metadata sidebar
- upload: drag-drop, sequential upload, progress tracking
- albums: create, add/remove photos, asset picker dialog
- admin: storage (import library), jobs (pagination, error details),
  plugins (list + toggle), pipelines, sidecars, duplicates
- multi-select mode with add-to-album action
- TanStack Query for all data fetching

k-photos-frontend/hooks/use-duplicates.ts

@@ -0,0 +1,35 @@
+"use client"
+
+import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query"
+import api from "@/lib/api"
+import type { DuplicateGroupResponse } from "@/lib/types"
+
+export function useDuplicates() {
+  return useQuery({
+    queryKey: ["admin", "duplicates"],
+    queryFn: async () => {
+      const { data } =
+        await api.get<DuplicateGroupResponse[]>("/duplicates")
+      return data
+    },
+  })
+}
+
+export function useResolveDuplicate() {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: async ({
+      groupId,
+      keepAssetId,
+    }: {
+      groupId: string
+      keepAssetId: string
+    }) => {
+      await api.post(`/duplicates/${groupId}/resolve`, {
+        keep_asset_id: keepAssetId,
+      })
+    },
+    onSuccess: () =>
+      qc.invalidateQueries({ queryKey: ["admin", "duplicates"] }),
+  })
+}