v6.7.3: faster loading, and pages search engines can read

The bundles carried all thirteen translations at once and a page fetched them a
third time as raw source; each page now loads only its own language. Alongside
that: JavaScript is minified, the eight stylesheets are served as one file, the
QR scanner is fetched after the app is up instead of on every visit, Inter ships
once rather than five copies of the same file, and Font Awesome is subset to the
82 icons this app draws instead of all 2468.

1.85 MB across 43 requests becomes under 700 KB across 33. On mobile the page
starts drawing in 1.6 s instead of 6.3 s and is usable in 4.5 s instead of 11 s.

Pages also carry their text in the HTML now. Everything was drawn by JavaScript
into an empty div, so crawlers saw correct metadata around nothing, and twelve of
the thirteen language pages had never been shown to anyone. The documentation is
published under /docs/ with a new FAQ, and unknown addresses return a real 404.

Separately: the localized shells were served with the year-long immutable cache
header meant for static assets, which pinned anyone who opened /de/ or /ru/ to
that build. The header is fixed and the service worker refreshes what it cached.

Claude-Session: https://claude.ai/code/session_014KjzTXxrhzYoDDWChYQ4u2

locales/ko.json

@@ -7,7 +7,6 @@
   "meta": {
     "title": "SecureBit.chat - 종단 간 암호화 비공개 메신저",
     "description": "SecureBit.chat은 브라우저 안에서만 동작하는 무료 P2P 메신저로, 종단 간 암호화를 사용합니다. 계정도 없고 메시지를 보관하는 서버도 없습니다 - ECDH P-384, AES-256-GCM, 그리고 직접 만나서 하는 SAS 확인.",
-    "keywords": "암호화 메신저, 종단 간 암호화, P2P 채팅, P2P 메신저, ECDH, DTLS, SAS 확인, WebRTC, 비공개 채팅, 안전한 채팅, 서버 없음, 계정 없음, 중간자 공격 방어, 순방향 비밀성",
     "ogTitle": "SecureBit.chat - 종단 간 암호화 P2P 채팅",
     "ogDescription": "브라우저 안에서만 동작하는 안전한 메신저입니다. 계정도 없고 메시지를 보관하는 서버도 없습니다. 직접 운영하는 STUN/TURN 서버를 쓸 수 있습니다 - 무엇도 강요하지 않습니다.",
     "ogImageAlt": "SecureBit.chat - 종단 간 암호화 P2P 채팅",