feat(navigator): useNavigatorSearch query hook (P2 core)

useNitroQuery keyed on [currentTabCode, currentFilter] from
navigatorUiStore. Fires NavigatorSearchComposer; subscribes to
NavigatorSearchEvent with an accept-filter that rejects results whose
code does not match the current tab. Invalidates on FlatCreatedEvent
and RoomSettingsUpdatedEvent for server-driven refresh.

nitro-renderer.mock.ts: add connection.send stub to GetCommunication
so SendMessageComposer (which calls GetCommunication().connection.send)
does not throw in tests that exercise useNitroQuery.

TDD: 7 cases incl. enabled-gating, accept-filter rejection on
mismatched tab, invalidator round-trip.

src/nitro-renderer.mock.ts

@@ -533,7 +533,9 @@ export const GetCommunication = vi.fn(() => ({
     {
         const wrapper = _msgEventWrappers.get(event);
         if(wrapper) msgListeners.get(event.type)?.delete(wrapper);
-    }
+    },
+    // Stub for SendMessageComposer which calls GetCommunication().connection.send(...)
+    connection: { send: vi.fn() }
 }));
 export const GetConfiguration = vi.fn(stubManager);
 export const GetLocalizationManager = vi.fn(stubManager);