feat: add SequencerPage with sequencer functionality including track and sound management

feat: implement SequencerCanvas for visualizing tracks and placed sounds
feat: create SoundLibrary for draggable sound selection
feat: add TimelineControls for managing duration and zoom levels
feat: implement TrackControls for adding, removing, and renaming tracks

src/App.tsx

@@ -13,6 +13,7 @@ import { PlaylistEditPage } from './pages/PlaylistEditPage'
 import { PlaylistsPage } from './pages/PlaylistsPage'
 import { RegisterPage } from './pages/RegisterPage'
 import { SchedulersPage } from './pages/SchedulersPage'
+import { SequencerPage } from './pages/SequencerPage'
 import { SoundsPage } from './pages/SoundsPage'
 import { SettingsPage } from './pages/admin/SettingsPage'
 import { UsersPage } from './pages/admin/UsersPage'
@@ -111,6 +112,14 @@ function AppRoutes() {
           </ProtectedRoute>
         }
       />
+      <Route
+        path="/sequencer"
+        element={
+          <ProtectedRoute>
+            <SequencerPage />
+          </ProtectedRoute>
+        }
+      />
       <Route
         path="/schedulers"
         element={