Split translations into per-language files, lazy-loaded

Only English is bundled in index.html now; the other 19 languages are
emitted as dist/locales/<code>.json and fetched on demand when a visitor
actually uses one (via auto-detect, the picker, or ?lang=xx). This drops
index.html from ~511KB to ~318KB; a non-English visitor fetches just
their one ~8-10KB locale, which the service worker then caches for
offline use. t() falls back to English until a locale resolves.

- i18n.js keeps only en + a loadLocale() fetcher; locale data moved to
  src/locales/*.json.
- build.js emits dist/locales/; dev.js serves /locales/<code>.json.
- Deploy hook publishes the locales/ subdir.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

1 files changed, 9 insertions, 1 deletions

diff --git a/dev.js b/dev.js
index dde8813..b1d64d8 100644
--- a/dev.js
+++ b/dev.js
@@ -9,11 +9,19 @@ Bun.serve({
   port,
   async fetch(req) {
     try {
-      if (new URL(req.url).pathname === '/jsqr.js') {
+      const path = new URL(req.url).pathname;
+      if (path === '/jsqr.js') {
         return new Response(await buildJsQr({ minify: false }), {
           headers: { 'content-type': 'text/javascript; charset=utf-8' },
         });
       }
+      const loc = path.match(/^\/locales\/([a-z]{2})\.json$/);
+      if (loc) {
+        const f = Bun.file('src/locales/' + loc[1] + '.json');
+        return (await f.exists())
+          ? new Response(f, { headers: { 'content-type': 'application/json; charset=utf-8' } })
+          : new Response('{}', { status: 404, headers: { 'content-type': 'application/json' } });
+      }
       const html = await buildHtml({ minify: false });
       return new Response(html, {
         headers: { 'content-type': 'text/html; charset=utf-8' },