fix(i18n): English-only until Lotus strings are localized

The language detector switched the few upstream-translated strings to
the browser locale while every Lotus surface stayed English, producing a
mixed UI. supportedLngs is now ['en']; the detector, backend and locale
files stay so re-enabling is one line plus routing Lotus strings through
useTranslation.

Fixes #53

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/i18n.ts

@@ -19,6 +19,16 @@ i18n
   .init<HttpBackendOptions>({
     debug: false,
     fallbackLng: 'en',
+    // Lotus Chat is English-only for now: none of the Lotus-added UI (presence,
+    // calls, soundboard, decorations, seasonal settings, keyboard shortcuts help,
+    // etc.) is routed through useTranslation()/public/locales yet, so letting
+    // LanguageDetector pick a non-English browser locale produced a UI that was
+    // only partially translated (the ~11 upstream strings switched language,
+    // everything Lotus-added stayed English). Restricting supportedLngs keeps
+    // the detector/backend/mechanism intact (see LOTUS_FEATURES.md) so other
+    // languages can come back with a one-line change once Lotus strings are
+    // localized.
+    supportedLngs: ['en'],
     interpolation: {
       escapeValue: false, // not needed for react as it escapes by default
     },