- Fixed `AssemblyAISTTService`, `CartesiaSTTService`, `GradiumSTTService`, and `SonioxSTTService` crashing the pipeline on transient WebSocket send failures. Each `run_stt` sent audio directly without catching errors, so a single network hiccup mid-stream raised an uncaught exception through `process_frame`. The guards now log a warning and let the connection-state check on the next call handle recovery, matching the pattern used by Deepgram, xAI, Azure, and other push-based STTs.
