refactor(query-keys): expand factory and migrate auth, notifications, about

Routes the registration-status, auth invalidation, notifications
preferences, and Settings about-section api-version reads through
the centralised queryKeys factory. Adds factory entries for the
remaining settings/admin surfaces a follow-up will migrate, and
extends the walker test to fail on any future bare-literal
queryKey in src/app/auth, src/app/notifications, and the
about-section. Also swaps the dashboard tile Suspense fallback
from null to a layout-stable card placeholder so a future RSC
hoist of any tile slot can't trigger CLS.

src/app/auth/login/page.tsx

@@ -85,7 +85,7 @@ export default function LoginPage() {
         return;
       }
 
-      await queryClient.invalidateQueries({ queryKey: ["auth"] });
+      await queryClient.invalidateQueries({ queryKey: queryKeys.auth() });
       router.push(getRedirectTarget());
     } catch (err) {
       const { key, params } = describePasskeyError(err);
@@ -114,7 +114,7 @@ export default function LoginPage() {
         return;
       }
 
-      await queryClient.invalidateQueries({ queryKey: ["auth"] });
+      await queryClient.invalidateQueries({ queryKey: queryKeys.auth() });
       router.push(getRedirectTarget());
     } catch {
       setError(t("auth.loginFailed"));

src/app/auth/register/page.tsx

@@ -12,6 +12,7 @@ import { Label } from "@/components/ui/label";
 import { PasswordStrength } from "@/components/ui/password-strength";
 import { useTranslations } from "@/lib/i18n/context";
 import { detectBrowserTimezone } from "@/lib/tz/format";
+import { queryKeys } from "@/lib/query-keys";
 
 export default function RegisterPage() {
   const router = useRouter();
@@ -54,7 +55,7 @@ export default function RegisterPage() {
         return;
       }
 
-      await queryClient.invalidateQueries({ queryKey: ["auth"] });
+      await queryClient.invalidateQueries({ queryKey: queryKeys.auth() });
       router.push("/");
     } catch {
       setError(t("auth.registerFailed"));

src/app/notifications/page.tsx

@@ -12,6 +12,7 @@ import {
   EVENT_DEFAULT_ENABLED,
   type EventType,
 } from "@/lib/notifications/types";
+import { queryKeys } from "@/lib/query-keys";
 
 interface ChannelInfo {
   id: string;
@@ -86,7 +87,7 @@ export default function NotificationsPage() {
   const queryClient = useQueryClient();
 
   const { data, isLoading, isError } = useQuery({
-    queryKey: ["notifications", "preferences"],
+    queryKey: queryKeys.notificationsPreferences(),
     queryFn: async () => {
       const res = await fetch("/api/notifications/preferences");
       if (!res.ok) throw new Error("Failed to load preferences");
@@ -112,12 +113,11 @@ export default function NotificationsPage() {
     },
     onMutate: async ({ channelId, eventType, enabled }) => {
       await queryClient.cancelQueries({
-        queryKey: ["notifications", "preferences"],
+        queryKey: queryKeys.notificationsPreferences(),
       });
-      const prev = queryClient.getQueryData<PreferencesData>([
-        "notifications",
-        "preferences",
-      ]);
+      const prev = queryClient.getQueryData<PreferencesData>(
+        queryKeys.notificationsPreferences(),
+      );
       if (prev) {
         const existing = prev.preferences.find(
           (p) => p.channelId === channelId && p.eventType === eventType,
@@ -130,7 +130,7 @@ export default function NotificationsPage() {
             )
           : [...prev.preferences, { channelId, eventType, enabled }];
         queryClient.setQueryData<PreferencesData>(
-          ["notifications", "preferences"],
+          queryKeys.notificationsPreferences(),
           { ...prev, preferences: newPreferences },
         );
       }
@@ -139,14 +139,14 @@ export default function NotificationsPage() {
     onError: (_err, _vars, context) => {
       if (context?.prev) {
         queryClient.setQueryData(
-          ["notifications", "preferences"],
+          queryKeys.notificationsPreferences(),
           context.prev,
         );
       }
     },
     onSettled: () => {
       queryClient.invalidateQueries({
-        queryKey: ["notifications", "preferences"],
+        queryKey: queryKeys.notificationsPreferences(),
       });
     },
   });

src/app/page.tsx

@@ -1413,7 +1413,25 @@ export default function DashboardPage() {
                      * future RSC hoists of any tile slot won't need a
                      * second pass to add the fallback infrastructure.
                      */}
-                    <Suspense fallback={null}>{entry.node}</Suspense>
+                    {/*
+                     * v1.4.41 W-FRONTEND-FACTORY (UX M1) — swap the
+                     * `null` fallback for a layout-stable placeholder
+                     * that mirrors the trend-card chrome. The body
+                     * stays synchronous today so the fallback rarely
+                     * paints, but a future RSC hoist of any tile slot
+                     * would otherwise leave the grid track empty and
+                     * trigger CLS as the cell paints in.
+                     */}
+                    <Suspense
+                      fallback={
+                        <div
+                          aria-hidden="true"
+                          className="bg-card border-border h-full w-full rounded-xl border p-4 md:p-6"
+                        />
+                      }
+                    >
+                      {entry.node}
+                    </Suspense>
                   </div>
                 ))}
               </div>