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/src/server/app-locale.functions.ts

@@ -0,0 +1,20 @@
+import { createServerFn } from "@tanstack/react-start"
+
+import { isAppLocale } from "@/i18n/app-locales"
+import { readAppLocale, writeAppLocale } from "./app-locale.server"
+
+export const getAppLocale = createServerFn({ method: "GET" }).handler(() => {
+  return readAppLocale()
+})
+
+export const setAppLocale = createServerFn({ method: "POST" })
+  .validator((value: unknown) => {
+    if (!isAppLocale(value)) {
+      throw new Error("Invalid app locale")
+    }
+
+    return value
+  })
+  .handler(({ data }) => {
+    writeAppLocale(data)
+  })