feat(speech): add realtime prompt dictation support

Add server-backed realtime transcription for prompt voice input and expose speech settings to choose realtime mode and models.

packages/ui/src/stores/preferences.tsx

@@ -34,6 +34,8 @@ export interface SpeechSettings {
   provider: SpeechProviderPreference
   apiKey?: string
   baseUrl?: string
+  useRealtime: boolean
+  realtimeModel: string
   sttModel: string
   ttsModel: string
   ttsVoice: string
@@ -136,6 +138,8 @@ const defaultUiSettings: UiSettings = {
 
 const defaultSpeechSettings: SpeechSettings = {
   provider: "openai-compatible",
+  useRealtime: true,
+  realtimeModel: "gpt-realtime",
   sttModel: "gpt-4o-mini-transcribe",
   ttsModel: "gpt-4o-mini-tts",
   ttsVoice: "alloy",
@@ -184,6 +188,11 @@ function normalizeSpeechSettings(input?: Partial<SpeechSettings> | null): Speech
     provider: sanitized.provider === "openai-compatible" ? sanitized.provider : defaultSpeechSettings.provider,
     apiKey: typeof sanitized.apiKey === "string" && sanitized.apiKey.trim() ? sanitized.apiKey.trim() : undefined,
     baseUrl: typeof sanitized.baseUrl === "string" && sanitized.baseUrl.trim() ? sanitized.baseUrl.trim() : undefined,
+    useRealtime: sanitized.useRealtime ?? defaultSpeechSettings.useRealtime,
+    realtimeModel:
+      typeof sanitized.realtimeModel === "string" && sanitized.realtimeModel.trim()
+        ? sanitized.realtimeModel.trim()
+        : defaultSpeechSettings.realtimeModel,
     sttModel:
       typeof sanitized.sttModel === "string" && sanitized.sttModel.trim()
         ? sanitized.sttModel.trim()