feat(dashboard): activate routed media filters

tests/dashboard/app.test.tsx

@@ -91,6 +91,52 @@ describe('dashboard foundation', () => {
     expect(screen.getByRole('heading', { name: 'Operations' })).toBeInTheDocument();
   });
 
+  it('hydrates media filters from the routed URL', async () => {
+    installSuccessfulApi();
+    server.use(
+      http.get('/api/media', () => HttpResponse.json([{
+        id: 'media-1',
+        chatUsername: 'alice',
+        chatRoomId: 'room-1',
+        sender: 'alice',
+        timestamp: Date.now(),
+        originalUrl: 'https://example.test/reaction.gif',
+        fileName: 'reaction.gif',
+        relativePath: 'reaction.gif',
+        createdAt: Date.now(),
+        urlPath: '/media/reaction.gif',
+      }])),
+      http.get('/api/media/sync', () => HttpResponse.json({
+        isSyncing: false,
+        lastSyncAt: null,
+        lastSyncDurationMs: null,
+        lastSyncChats: null,
+        lastError: null,
+        nextSyncAt: null,
+      })),
+      http.get('/api/login/status', () => HttpResponse.json({
+        ready: true,
+        loggedIn: true,
+        status: 'authenticated',
+      })),
+      http.get('/api/chats/sync', () => HttpResponse.json({
+        syncing: false,
+        syncingKind: null,
+        lastFullSyncAt: null,
+        lastDeltaSyncAt: null,
+        hasEverFullSynced: false,
+        cachedChats: 0,
+        progress: null,
+      })),
+    );
+
+    renderDashboard('/media?conversation=alice&type=gif&range=7d');
+
+    expect(await screen.findByRole('combobox', { name: 'Conversation' })).toHaveValue('alice');
+    expect(screen.getByRole('combobox', { name: 'Media type' })).toHaveValue('gif');
+    expect(screen.getByRole('combobox', { name: 'Date range' })).toHaveValue('7d');
+  });
+
   it('shows loading then renders stats, timers, and an explicit empty activity state', async () => {
     let resolveStats: ((response: Response) => void) | undefined;
     server.use(