fix: set accepted user agent for APInex STT

bot.py

@@ -52,6 +52,7 @@ async def transcribe_audio(audio: bytes, content_type: str, api_key: str) -> str
         "Authorization": f"Bearer {api_key}",
         "Content-Type": content_type,
         "Accept": "application/json",
+        "User-Agent": "Mozilla/5.0 (compatible; SocialPostWriterBot/1.0)",
     }
     async with aiohttp.ClientSession(timeout=timeout) as session:
         async with session.post(APINEX_STT_URL, data=audio, headers=headers) as response:

tests/test_voice_stt.py

@@ -61,6 +61,7 @@ class VoiceSttTests(unittest.IsolatedAsyncioTestCase):
         self.assertEqual(kwargs["data"], b"ogg-data")
         self.assertEqual(kwargs["headers"]["Content-Type"], "audio/ogg")
         self.assertEqual(kwargs["headers"]["Authorization"], "Bearer not-logged")
+        self.assertIn("Mozilla/5.0", kwargs["headers"]["User-Agent"])
 
     async def test_transcribe_raises_on_api_error(self):
         fake_session = FakeClientSession(FakeResponse(401, {}))