feat: add preferred STT languages and fix model settings layout

src/core/i18n.ts

@@ -63,8 +63,11 @@ export function learningLanguageInstruction(language: Language): string {
 		: "LANGUAGE: Use English for all learner-facing content, including teaching, questions and choices, plans, titles, practice, research summaries, knowledge-graph propositions, and text in generated diagrams, figures and demos. Preserve code, notation, identifiers, proper names and quoted source text. Follow an explicit learner request for a different language or a language-learning exercise when necessary.";
 }
 /** Streaming configuration: the language is pinned once at recording start, including reconnects. */
-export function dictationUrl(language: SttLanguage): string {
+export function dictationUrl(language: SttLanguage, preferredLanguages: readonly Language[] = []): string {
 	const params = new URLSearchParams({ model: "nova-3", language, encoding: "linear16", sample_rate: "16000", channels: "1", smart_format: "true", punctuate: "true", endpointing: "300" });
+	if (language === "multi") {
+		for (const preferred of new Set(preferredLanguages)) if (isLanguage(preferred)) params.append("language_hint", preferred);
+	}
 	return `wss://api.deepgram.com/v1/listen?${params}`;
 }