feat: share heaps and folders with other users, fix auth and vision pipeline

Sharing:
- New HeapShare and FolderShare models with read/write permissions
- Sharing API router (CRUD for heap and folder shares)
- Heap endpoints accept shared access (photo_ids, add/remove with write)
- Photo list drops user_id filter in shared context, adds owner_username
- Media serving (thumb/original/proxy) falls back to share check on 404
- ShareDialog component for managing shares from kebab menus
- HeapsPanel shows "Shared with me" section for shared heaps
- LeftSidebar shows "Shared with me" section for shared folders
- Owner badge on PhotoThumbnail for photos from other users

Auth:
- Access token default bumped to 1 year, refresh to 10 years
- Refresh token persisted in localStorage (survives page reload)
- Timer-based refresh replaced with 401 axios interceptor

Vision pipeline fixes:
- Bootstrap sets Redis ready key even on partial export failure
- Export functions run conditionally (only for actually missing models)
- _load_thumb handles multi-user path (/data/thumbs/{user_id}/{photo_id}/)
- can_access_photo_via_share uses single subquery instead of N+1 loop

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/hooks/useSharingQueries.ts

@@ -0,0 +1,21 @@
+import { useQuery } from '@tanstack/react-query'
+import { sharing, type SharedHeap, type SharedFolder } from '../services/api'
+
+export const SHARED_HEAPS_KEY = ['sharing', 'heaps'] as const
+export const SHARED_FOLDERS_KEY = ['sharing', 'folders'] as const
+
+export function useSharedHeapsQuery() {
+  return useQuery<SharedHeap[]>({
+    queryKey: SHARED_HEAPS_KEY,
+    queryFn: sharing.sharedHeaps,
+    staleTime: 30_000,
+  })
+}
+
+export function useSharedFoldersQuery() {
+  return useQuery<SharedFolder[]>({
+    queryKey: SHARED_FOLDERS_KEY,
+    queryFn: sharing.sharedFolders,
+    staleTime: 30_000,
+  })
+}