Serve the site in English, Spanish and Arabic, add a captcha, make the message optional

- Move every route under app/[lang]; a proxy keeps English on unprefixed URLs and serves /es and /ar
- Interface strings and homepage copy per locale; content pages load a translated JSON when one exists
- Language switch in the header, hreflang alternates and a multilingual sitemap
- Right-to-left layout for Arabic with logical CSS properties, Noto Sans Arabic and no letter-spacing
- Self-hosted proof-of-work "I'm not a robot" check (no third-party account) replaces Turnstile
- The message field is optional; failed attempts refill the form instead of clearing it

src/i18n/ui/index.ts

@@ -0,0 +1,7 @@
+import type { Locale } from "../config";
+import { en, type UI } from "./en";
+import { es } from "./es";
+import { ar } from "./ar";
+
+export type { UI };
+export const ui: Record<Locale, UI> = { en, es, ar };