feat(navigator): wired-tools-style hook split (Store + 3 filters)

Splits the 492-line useNavigator god-hook into a useBetween-backed
useNavigatorStore closure plus three flat-shape filters
(useNavigatorData, useNavigatorUiState, useNavigatorActions), mirroring
the wired-tools layout. sendSearch + reloadCurrentSearch are extracted
as named actions out of NavigatorView locals.

Door-mode handling is removed from this store and lives in useDoorState
(committed previously) - see GetGuestRoomResultEvent and
GenericErrorEvent dual-subscription with mutually exclusive filters.

The simpleAlert dependency is lifted out of the useBetween scope via a
module-level _simpleAlert ref + _injectSimpleAlert() to avoid nested
useBetween calls that corrupt use-between's module-level dispatcher
state. The ref is null in tests (no events fire during smoke tests) and
is populated in production by the navigator consumer before any alert
is needed.

The barrel index.ts no longer re-exports useNavigator. The 13 consumers
will fail typecheck until the next commit migrates them; the hook files
themselves are clean. Smoke test covers filter shapes.

INTENTIONAL INTERMEDIATE-BROKEN COMMIT: yarn typecheck is RED at this
SHA on the 13 consumer files. The next commit (consumer migration sweep)
brings it back to green.

src/hooks/navigator/useNavigatorUiState.ts

@@ -0,0 +1,18 @@
+import { useNavigatorUiStore } from './navigatorUiStore';
+
+export const useNavigatorUiState = () =>
+{
+    const isVisible           = useNavigatorUiStore(s => s.isVisible);
+    const isReady             = useNavigatorUiStore(s => s.isReady);
+    const isCreatorOpen       = useNavigatorUiStore(s => s.isCreatorOpen);
+    const isRoomInfoOpen      = useNavigatorUiStore(s => s.isRoomInfoOpen);
+    const isRoomLinkOpen      = useNavigatorUiStore(s => s.isRoomLinkOpen);
+    const isOpenSavesSearches = useNavigatorUiStore(s => s.isOpenSavesSearches);
+    const isLoading           = useNavigatorUiStore(s => s.isLoading);
+    const needsInit           = useNavigatorUiStore(s => s.needsInit);
+    const needsSearch         = useNavigatorUiStore(s => s.needsSearch);
+    return {
+        isVisible, isReady, isCreatorOpen, isRoomInfoOpen, isRoomLinkOpen,
+        isOpenSavesSearches, isLoading, needsInit, needsSearch
+    };
+};