feat(router): handle 9 new Telegram update types

[wrxck]

Summary

• Add handler functions and api.run() wiring for: chat_join_request, chat_member, my_chat_member, message_reaction, poll, poll_answer, chat_boost, removed_chat_boost, message_reaction_count
• Each handler uses a lightweight context builder (no full middleware pipeline) and dispatches to plugin hooks following existing patterns
• Fix callback_query handler to create valid chat context for inline buttons (was creating empty {} chat object)
• Update allowed_updates list with all new types

Test plan

• Join a group that has the bot — verify on_chat_join_request fires
• React to messages — verify on_message_reaction fires
• Create a poll — verify on_poll and on_poll_answer fire
• Boost a chat — verify on_chat_boost fires
• Verify existing message/callback/inline handling still works

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