feat(telegram): forum topic support via message_thread_id

[leyten]

Telegram forum supergroups split conversations into topics. Without message_thread_id, the bot's replies always land in the General feed even when the inbound message came from a sub-topic, which is jarring for users running an MCP-driven Claude in a multi-topic group.

This change:

• Surfaces the inbound topic on the tag as a message_thread_id attribute (omitted for General / non-forum chats).
• Adds an optional message_thread_id parameter to the reply tool and threads it through sendMessage / sendPhoto / sendDocument so replies land in the originating topic.
• Updates the reply tool description and the server instructions block so the model knows to pass message_thread_id back through.

Backwards compatible: regular groups, DMs, and the General topic of a forum group never carry message_thread_id, so existing flows are unchanged.

[github-actions]

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