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/src/routes/terms/+page.svelte

@@ -1,5 +1,9 @@
+<script lang="ts">
+	import * as m from '$lib/paraglide/messages.js';
+</script>
+
 <svelte:head>
-	<title>Terms of Service — libnovel</title>
+	<title>{m.terms_page_title()}</title>
 </svelte:head>
 
 <div class="max-w-2xl mx-auto py-10 px-4">