feat: timeline and folder import

frontend/src/App.tsx

@@ -3,6 +3,10 @@ import { Timeline } from './components/timeline/Timeline'
 import { LeftSidebar } from './components/layout/LeftSidebar'
 import { RightSidebar } from './components/layout/RightSidebar'
 import { TopBar } from './components/layout/TopBar'
+import { ScanProgress } from './components/ScanProgress'
+import { ToastContainer } from './components/ToastContainer'
+import { KeyboardShortcuts } from './components/KeyboardShortcuts'
+import { KeyboardHints } from './components/KeyboardHints'
 import { usePhotoStore } from './store/photoStore'
 import { useKeyboardShortcuts } from './hooks/useKeyboardShortcuts'
 
@@ -52,6 +56,18 @@ function App() {
           <RightSidebar />
         </div>
       </div>
+      
+      {/* Contextual Keyboard Hints */}
+      <KeyboardHints />
+      
+      {/* Keyboard Shortcuts Legend */}
+      <KeyboardShortcuts />
+      
+      {/* Scan Progress Indicator */}
+      <ScanProgress />
+      
+      {/* Toast Notifications */}
+      <ToastContainer />
     </div>
   )
 }