fix(tts): use opus format and enable voice bubbles for feishu and whatsapp (#27366)

* fix(tts): use opus format and enable voice bubbles for feishu and whatsapp

Previously only Telegram received opus output and had `shouldVoice=true`.
Feishu and WhatsApp also support voice-bubble playback and require opus audio,
but were falling back to mp3 with `audioAsVoice=false`.

- Extract VOICE_BUBBLE_CHANNELS set (telegram, feishu, whatsapp)
- resolveOutputFormat: return TELEGRAM_OUTPUT (opus) for all voice-bubble channels
- shouldVoice: enable for all voice-bubble channels, not just telegram
- Update test to cover feishu and whatsapp cases

* Changelog: add TTS voice-bubble channel coverage note

---------

Co-authored-by: Ning Hu <ninghu@Nings-MacBook-Pro.local>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/tts/tts.test.ts

@@ -154,7 +154,7 @@ describe("tts", () => {
   });
 
   describe("resolveOutputFormat", () => {
-    it("selects opus for Telegram and mp3 for other channels", () => {
+    it("selects opus for voice-bubble channels (telegram/feishu/whatsapp) and mp3 for others", () => {
       const cases = [
         {
           channel: "telegram",
@@ -165,6 +165,24 @@ describe("tts", () => {
             voiceCompatible: true,
           },
         },
+        {
+          channel: "feishu",
+          expected: {
+            openai: "opus",
+            elevenlabs: "opus_48000_64",
+            extension: ".opus",
+            voiceCompatible: true,
+          },
+        },
+        {
+          channel: "whatsapp",
+          expected: {
+            openai: "opus",
+            elevenlabs: "opus_48000_64",
+            extension: ".opus",
+            voiceCompatible: true,
+          },
+        },
         {
           channel: "discord",
           expected: {