fix: dedicate watcher to own worker, fix media auth + memories nav

- Move watch_folders to dedicated 'watcher' queue with its own
  single-concurrency container so it never blocks scan/thumbnail slots
- Add get_current_user_media dependency that accepts ?token= query
  param for <img src> / <video src> media endpoints (thumb, original,
  proxy) — fixes 401 on thumbnails
- Append JWT token to all media URLs in the frontend
- Add missing 'memories' case in sidebar navigation switch

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

frontend/src/components/layout/LeftSidebar.tsx

@@ -276,6 +276,9 @@ export function LeftSidebar({ onCollapse }: LeftSidebarProps) {
       case 'map':
         navigateToSection('map', {})
         break
+      case 'memories':
+        navigateToSection('memories', {})
+        break
       default:
         if (id.startsWith('folder-')) {
           const folderId = id.slice('folder-'.length)

frontend/src/components/memories/MemoriesView.tsx

@@ -1,5 +1,5 @@
 import { useQuery } from '@tanstack/react-query'
-import { photos } from '../../services/api'
+import { photos, photos as photosApi } from '../../services/api'
 import type { MemoryGroup } from '../../services/api'
 
 export function MemoriesView() {
@@ -47,7 +47,7 @@ export function MemoriesView() {
               >
                 {photo.thumb_small ? (
                   <img
-                    src={`/api/v1/photos/${photo.id}/thumb/small`}
+                    src={photosApi.getThumbnailUrl(photo.id, 'small')}
                     alt={photo.filename}
                     className="w-full h-full object-cover"
                     loading="lazy"