feat(agent): add voice message support with TTS/STT for Telegram and WeChat

- Integrate voice message handling: detect and extract audio references from Telegram and WeChat messages, route to agent with voice reply preference.
- Add voice provider abstraction and OpenAI-based TTS/STT implementation.
- Implement agent tool `send_voice_message` for generating and sending voice replies, with fallback to text if voice is unavailable.
- Extend agent prompt and context to support voice reply instructions.
- Update notification and message schemas to support audio fields.
- Add Telegram and WeChat voice sending logic, including audio file conversion and temporary media upload for WeChat.
- Add tests for voice helper and agent voice routing.

tests/test_voice_helper.py

@@ -0,0 +1,55 @@
+import unittest
+import sys
+from unittest.mock import Mock, patch
+
+sys.modules.setdefault("psutil", Mock())
+sys.modules.setdefault("pyquery", Mock())
+
+from app.core.config import settings
+from app.helper.voice import VoiceHelper, OpenAIVoiceProvider
+
+
+class VoiceHelperTest(unittest.TestCase):
+    def test_registered_providers_contains_openai(self):
+        self.assertIn("openai", VoiceHelper.get_registered_providers())
+
+    def test_get_provider_falls_back_to_global_provider(self):
+        with patch.object(settings, "AI_VOICE_PROVIDER", "openai"), patch.object(
+            settings, "AI_VOICE_STT_PROVIDER", None
+        ):
+            provider = VoiceHelper.get_provider("stt")
+
+        self.assertIsInstance(provider, OpenAIVoiceProvider)
+
+    def test_is_available_checks_stt_and_tts_separately(self):
+        provider = Mock()
+        provider.is_available_for_stt.return_value = True
+        provider.is_available_for_tts.return_value = False
+
+        with patch.object(VoiceHelper, "get_provider", return_value=provider):
+            self.assertTrue(VoiceHelper.is_available("stt"))
+            self.assertFalse(VoiceHelper.is_available("tts"))
+
+    def test_transcribe_bytes_routes_to_stt_provider(self):
+        provider = Mock()
+        provider.transcribe_bytes.return_value = "你好"
+
+        with patch.object(VoiceHelper, "get_provider", return_value=provider):
+            result = VoiceHelper.transcribe_bytes(b"audio")
+
+        self.assertEqual(result, "你好")
+        provider.transcribe_bytes.assert_called_once()
+
+    def test_synthesize_speech_routes_to_tts_provider(self):
+        provider = Mock()
+        provider.synthesize_speech.return_value = "/tmp/reply.opus"
+
+        with patch.object(VoiceHelper, "get_provider", return_value=provider):
+            result = VoiceHelper.synthesize_speech("你好")
+
+        self.assertEqual(result, "/tmp/reply.opus")
+        provider.synthesize_speech.assert_called_once_with(text="你好")
+
+
+if __name__ == "__main__":
+    unittest.main()