feat(i18n): add Paraglide i18n with 5 locales (v2.3.22)

- Install @inlang/paraglide-js v2.15.1; configure project.inlang settings
- Add en/ru/id/pt-BR/fr message catalogues (~140 keys each)
- Wire paraglideVitePlugin in vite.config.ts, reroute hook in hooks.ts,
  and paraglideHandle middleware in hooks.server.ts
- Migrate all routes and shared components to use m.*() message calls
- Fix duplicate onMount body in chapters/[n]/+page.svelte
- Build passes; svelte-check: 0 errors, 3 pre-existing warnings

ui/package.json

@@ -30,6 +30,7 @@
 	"dependencies": {
 		"@aws-sdk/client-s3": "^3.1005.0",
 		"@aws-sdk/s3-request-presigner": "^3.1005.0",
+		"@inlang/paraglide-js": "^2.15.1",
 		"@opentelemetry/exporter-logs-otlp-http": "^0.214.0",
 		"@opentelemetry/exporter-trace-otlp-http": "^0.214.0",
 		"@opentelemetry/resources": "^2.6.1",