feat(web): integrate localized application catalogs

- compose app, UI, and independently imported block catalogs from JSON configuration\n- persist the selected locale on the server and activate it without hydration flicker\n- add a flag-based language switcher and localized navigation descriptors\n- mount the redesigned i18n devtool only in development\n- regenerate English and Simplified Chinese catalogs and add switcher coverage

apps/web/i18n.config.json

@@ -2,6 +2,14 @@
   "sourceLocale": "en",
   "locales": ["en", "zh-Hans"],
   "catalogPath": "src/locales/{locale}/messages",
+  "catalogSources": [
+    "@workspace/ui/locales/{locale}",
+    "@workspace/blocks/appearance/locales/{locale}",
+    "@workspace/blocks/chats/locales/{locale}",
+    "@workspace/blocks/layout/locales/{locale}",
+    "@workspace/blocks/navigation/locales/{locale}",
+    "@workspace/blocks/notifications/locales/{locale}"
+  ],
   "include": ["src", "../../packages/blocks/src", "../../packages/ui/src"],
   "exclude": ["**/*.test.{ts,tsx}", "**/node_modules/**"]
 }