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/hooks/navigator/useNavigatorSearch.ts

@@ -0,0 +1,47 @@
+import { FlatCreatedEvent, NavigatorSearchComposer, NavigatorSearchEvent,
+    NavigatorSearchResultSet, RoomSettingsUpdatedEvent } from '@nitrots/nitro-renderer';
+import { useNitroEventInvalidator, useNitroQuery } from '../../api/nitro-query';
+import { useNavigatorUiStore } from './navigatorUiStore';
+
+const SEARCH_BASE_KEY = [ 'navigator', 'search' ] as const;
+
+/**
+ * TanStack Query wrapper for navigator search.
+ *
+ * Cache key: ['navigator', 'search', tabCode, filter]
+ * - Fires NavigatorSearchComposer(tabCode, filter) on miss.
+ * - Listens for NavigatorSearchEvent and resolves with the result.
+ * - accept-filter: rejects events whose result.code !== tabCode (defends
+ *   against server-side cross-tab pushes resolving the wrong query slot).
+ * - Disabled when tabCode is '' (initial state, before metadata arrives).
+ * - Invalidates on FlatCreatedEvent (new room created) and
+ *   RoomSettingsUpdatedEvent (room renamed / settings changed).
+ */
+export const useNavigatorSearch = () =>
+{
+    const tabCode = useNavigatorUiStore(s => s.currentTabCode);
+    const filter  = useNavigatorUiStore(s => s.currentFilter);
+
+    const query = useNitroQuery<NavigatorSearchEvent, NavigatorSearchResultSet | null>({
+        key: [ ...SEARCH_BASE_KEY, tabCode, filter ],
+        request: () => new NavigatorSearchComposer(tabCode, filter),
+        parser: NavigatorSearchEvent,
+        select: e => e.getParser()?.result ?? null,
+        accept: e =>
+        {
+            const result = e.getParser()?.result;
+            return !!result && result.code === tabCode;
+        },
+        enabled: !!tabCode,
+        staleTime: 30_000
+    });
+
+    useNitroEventInvalidator(FlatCreatedEvent, [ ...SEARCH_BASE_KEY ]);
+    useNitroEventInvalidator(RoomSettingsUpdatedEvent, [ ...SEARCH_BASE_KEY ]);
+
+    return {
+        searchResult: query.data ?? null,
+        isFetching: query.isFetching,
+        refetch: query.refetch
+    };
+};