fix(i18n): hydrate in the SSR locale instead of regressing to en

The client's message cache held only en at hydration, so a non-en user
rendered English until the locale's catalog chunk loaded — and stayed
English if that import failed or lost a race. __root beforeLoad now
dehydrates the active locale's compiled catalog with the page and the
provider primes its cache from that payload, so first paint is already in
the user's locale with no dependency on a client-side chunk load.
ensureMessages dedupes concurrent loads and drops rejected ones so a
retry can succeed, and the provider's fallback loader retries instead of
silently stranding the UI in en.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0189ASmkMee4F5aJ3jnKeKQv

src/app/routes/__root.tsx

@@ -18,7 +18,13 @@ import { ColorSchemeScript, mantineHtmlProps } from "@mantine/core";
 import { HeaderConfig } from "@/features/core/types/header-config";
 import { playerQueries } from "@/features/players/queries";
 import { ensureServerQueryData } from "@/lib/tanstack-query/utils/ensure";
-import { DEFAULT_LOCALE, ensureMessages, resolveLocale } from "@/lib/i18n";
+import {
+  DEFAULT_LOCALE,
+  ensureMessages,
+  getCachedMessages,
+  i18nMessagesQueryKey,
+  resolveLocale,
+} from "@/lib/i18n";
 import { getRootMeta } from "@/lib/i18n/meta";
 import FullScreenLoader from "@/components/full-screen-loader";
 import { CHROME_COLORS } from "@/lib/mantine/theme-colors";
@@ -132,7 +138,16 @@ export const Route = createRootRouteWithContext<{
         context.queryClient,
         playerQueries.auth()
       );
-      await ensureMessages(resolveLocale(auth?.metadata?.locale));
+      const locale = resolveLocale(auth?.metadata?.locale);
+      await ensureMessages(locale);
+      // Dehydrate the catalog with the page so the client hydrates in the
+      // active locale instead of falling back to en until a chunk loads.
+      if (typeof window === "undefined" && locale !== DEFAULT_LOCALE) {
+        context.queryClient.setQueryData(
+          i18nMessagesQueryKey(locale),
+          getCachedMessages(locale)
+        );
+      }
       return { auth };
     } catch (error: any) {
       if (isRedirect(error) || error instanceof Response) throw error;