build web with optional ui languages

interface/src/vite-env.d.ts

@@ -1 +1,13 @@
 /// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  // Optional comma-separated allow-list of locales to ship (e.g. "en,de,nl").
+  // Unset => all locales are bundled and embedded. `en` is always kept as the
+  // fallback. Consumed by App.tsx (UI language list) and progmem-generator.js
+  // (which locale chunks get embedded into firmware flash).
+  readonly VITE_APP_LOCALES?: string;
+}
+
+interface ImportMeta {
+  readonly env: ImportMetaEnv;
+}