feat: telegram voice transcription (#74)

docs/transports/telegram.md

@@ -16,6 +16,24 @@ This document captures current behavior so transport changes stay intentional.
 4. High-value messages enqueue a send.
 5. All writes go through the outbox.
 
+## Incoming messages
+
+`parse_incoming_update` accepts text messages and voice notes.
+
+If voice transcription is enabled, takopi downloads the voice payload from Telegram,
+transcribes it with OpenAI, and routes the transcript through the same command and
+directive pipeline as typed text.
+
+Configuration (under `[transports.telegram]`):
+
+```toml
+voice_transcription = true
+```
+
+Set `OPENAI_API_KEY` in the environment. If transcription is enabled but the API key
+is missing or the audio download fails, takopi replies with a short error and skips
+the run.
+
 ## Outbox model
 
 - Single worker processes one op at a time.