perf: lazy-load locale files per language instead of bundling all

Split 574KB monolithic locales chunk into per-language lazy chunks:
- ru: 211KB (loaded on startup as fallback)
- fa: 143KB, en: 121KB, zh: 101KB (loaded on demand)

Russian users save 63% bandwidth. Other languages loaded only when
user switches via LanguageSwitcher.

vite.config.ts

@@ -36,7 +36,6 @@ export default defineConfig({
     rollupOptions: {
       output: {
         manualChunks(id) {
-          if (id.includes('/src/locales/')) return 'locales';
           if (!id.includes('node_modules')) return;
           if (
             id.includes('react-dom') ||