TTS: add missing OpenAI voices (ballad, cedar, juniper, marin, verse) (openclaw#11020) thanks @lailoo

Verified:
- pnpm install --frozen-lockfile
- pnpm build
- pnpm check
- pnpm test

Co-authored-by: ${pr_author_login} <${coauthor_email}>
Co-authored-by: ${tak_name} <${tak_email}>

src/tts/tts.ts

@@ -842,13 +842,18 @@ function isCustomOpenAIEndpoint(): boolean {
 export const OPENAI_TTS_VOICES = [
   "alloy",
   "ash",
+  "ballad",
+  "cedar",
   "coral",
   "echo",
   "fable",
+  "juniper",
+  "marin",
   "onyx",
   "nova",
   "sage",
   "shimmer",
+  "verse",
 ] as const;
 
 type OpenAiTtsVoice = (typeof OPENAI_TTS_VOICES)[number];