Various build shenenigans (#5)

This PR extends the build pipeline of the www service to support
locale-prefixed static builds (EN/RU) with build-time SSG output
injection, while also refactoring UI typography to a tokenized Tailwind
v4 @theme-driven approach.

Changes:

- Add build-time SSG plugin to @ermnvldmr/rsbuild-config and wire
multi-locale builds (/en/, /ru/) into services/www.
- Introduce new @ermnvldmr/i18n package (locale constants, path helpers,
keysets, pluralization) and apply it to www navigation/text.
- Refactor ui typography to a shared getTypographyClassNames utility +
Tailwind token definitions, with stl/cn updated for correct
Tailwind-merge behavior.

packages/stl/src/lib/react/useLocalStorage/useLocalStorage.ts

@@ -39,9 +39,8 @@ export function useLocalStorage<T>(
   const getSnapshot = useCallback(() => manager.get(), [manager]);
 
   const value = useSyncExternalStore(subscribe, getSnapshot, () => {
-    // During SSR, we can't access localStorage.
-    // However, createLocalStorage is designed to throw if accessed during SSR.
-    // This hook is intended to be used in client-side components.
+    // SSR snapshot: createLocalStorage returns a no-op manager in Node context,
+    // so manager.get() safely returns defaultValue without accessing localStorage.
     return manager.get();
   });