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

src/i18n/index.js

@@ -11,10 +11,33 @@
  * language the recipient happened to pick last, which makes links unshareable.
  */
 
-import { DEFAULT_LOCALE, SUPPORTED_LOCALES, LOCALE_META, DICTIONARIES } from './generated.js';
+import { DEFAULT_LOCALE, SUPPORTED_LOCALES, LOCALE_META, CROSS_LOCALE_STRINGS } from './generated.js';
+// Side-effect import: loading the default locale's dictionary registers the strings
+// t() falls back to when a translation is missing a key. It is the one dictionary that
+// has to be present on every page, so it is the one that gets bundled.
+import './dict/default.js';
 
 export { DEFAULT_LOCALE, SUPPORTED_LOCALES, LOCALE_META };
 
+/**
+ * Loaded dictionaries, by locale code.
+ *
+ * On a global rather than in module scope, and that is the point. index.js exists twice
+ * on a page: once bundled inside dist/app.js, and once as raw source, because the PWA
+ * install prompt, the PWA manager and the update checker import it directly. Two module
+ * instances mean two module-scoped registries, and the /ru/ dictionary loaded by the
+ * page would have been invisible to the half of the app that needed it.
+ *
+ * A page loads its own dictionary through a <script type="module"> that runs before the
+ * bundles; every locale other than the default arrives that way. See scripts/build-i18n.js.
+ */
+const REGISTRY = globalThis.__SECUREBIT_I18N__ || (globalThis.__SECUREBIT_I18N__ = Object.create(null));
+
+/** The dictionary for a locale, or an empty one if that locale was never loaded. */
+function dictionary(code) {
+    return REGISTRY[code] || null;
+}
+
 const STORAGE_KEY = 'securebit-locale';
 
 /** The locale a path belongs to, or null for the default locale at the root. */
@@ -191,7 +214,7 @@ export function suggestedLocale({ pathname = '/', languages = [], stored = null
  * the count belongs to the translation, not to the component.
  */
 export function tList(key, locale = currentLocale()) {
-    const value = DICTIONARIES[locale]?.[key] ?? DICTIONARIES[DEFAULT_LOCALE]?.[key];
+    const value = dictionary(locale)?.[key] ?? dictionary(DEFAULT_LOCALE)?.[key];
     return Array.isArray(value) ? value : [];
 }
 
@@ -224,8 +247,12 @@ export function languageLinks({ pathname = '/', active = DEFAULT_LOCALE } = {})
  */
 export function t(key, vars, locale = currentLocale()) {
     const template =
-        DICTIONARIES[locale]?.[key] ??
-        DICTIONARIES[DEFAULT_LOCALE]?.[key] ??
+        dictionary(locale)?.[key] ??
+        // Asked for a locale whose dictionary is not on this page. Only the language
+        // suggestion does that, and only for the handful of keys it needs, so those
+        // ship for every locale; anything else falls through to the default below.
+        CROSS_LOCALE_STRINGS[locale]?.[key] ??
+        dictionary(DEFAULT_LOCALE)?.[key] ??
         key;
     if (!vars) return template;
     return String(template).replace(/\{(\w+)\}/g, (match, name) =>