fix(ui): mount ImageViewer globally so tile clicks open as overlay, not route-redirect to /gallery

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/views/GalleryView.vue

@@ -18,10 +18,6 @@
       <TimelineSidebar v-if="store.images.length > 0" class="fc-gallery-layout__sidebar" />
     </div>
 
-    <ImageViewer
-      v-if="modal.currentImageId !== null"
-      @close="closeImage"
-    />
     <BulkEditorPanel />
   </v-container>
 </template>
@@ -35,7 +31,6 @@ import GalleryGrid from '../components/gallery/GalleryGrid.vue'
 import TimelineSidebar from '../components/gallery/TimelineSidebar.vue'
 import EmptyState from '../components/gallery/EmptyState.vue'
 import PostInfoHeader from '../components/gallery/PostInfoHeader.vue'
-import ImageViewer from '../components/modal/ImageViewer.vue'
 import BulkEditorPanel from '../components/gallery/BulkEditorPanel.vue'
 import { useGallerySelectionStore } from '../stores/gallerySelection.js'