feat(telegram): coalesce forwarded messages (#146)

docs/reference/config.md

@@ -30,6 +30,7 @@ chat_id = 123
 | `bot_token` | string | (required) | Telegram bot token from @BotFather. |
 | `chat_id` | int | (required) | Default chat id. |
 | `message_overflow` | `"trim"`\|`"split"` | `"trim"` | How to handle long final responses. |
+| `forward_coalesce_s` | float | `1.0` | Quiet window for combining a prompt with immediately-following forwarded messages; set `0` to disable. |
 | `voice_transcription` | bool | `false` | Enable voice note transcription. |
 | `voice_max_bytes` | int | `10485760` | Max voice note size (bytes). |
 | `voice_transcription_model` | string | `"gpt-4o-mini-transcribe"` | OpenAI transcription model name. |
@@ -106,4 +107,3 @@ model = "..."
 ```
 
 The shape is engine-defined.
-