feat: Add ErrorFrame emission to TTS/STT services for pipeline error detection (#2881)

* feat: Add ErrorFrame emission to TTS/STT services for pipeline error detection

- Add ErrorFrame emission to all major TTS/STT services during initialization and runtime failures
- Services updated: Cartesia, ElevenLabs, Deepgram, AssemblyAI, Rime, Azure
- ErrorFrame objects emitted with fatal=False for graceful degradation
- Enables on_pipeline_error event handler to detect service failures programmatically
- Add comprehensive pytest test suite to verify ErrorFrame emission
- Fixes issue where services failed gracefully but didn't emit ErrorFrame objects

This allows developers to implement real-time error monitoring and alerting
using the on_pipeline_error event handler introduced in v0.0.90.

* Update STT and TTS services to use consistent error handling pattern

- Improves error handling consistency across all services

* Add changelog entry for STT/TTS error handling improvements

* Linting issues Resolved

* Azure STT ErrorFrames added with consistent patterns

* Cartesia STT and Deepgram STT; additional fixes made

* Removed Fatal Flags across services, removed duplication

* Moving the changelog entry to the correct place.

* Refactoring some classes to use yield instead of push_error directly.

* Fixing ruff format.

---------

Co-authored-by: Filipi Fuchter <filipi87@gmail.com>

src/pipecat/services/hume/tts.py

@@ -225,8 +225,8 @@ class HumeTTSService(TTSService):
                 self._audio_bytes = b""
 
         except Exception as e:
-            logger.exception(f"{self} error generating TTS: {e}")
-            await self.push_error(ErrorFrame(f"Error generating TTS: {e}"))
+            logger.error(f"{self} exception: {e}")
+            await self.push_error(ErrorFrame(error=f"{self} error: {e}"))
         finally:
             # Ensure TTFB timer is stopped even on early failures
             await self.stop_ttfb_metrics()