Previously, grammY's default bot.start() processed updates sequentially,
blocking all Telegram messages while one was being handled. This made
maxConcurrent settings ineffective for Telegram.
Now uses @grammyjs/runner which processes updates concurrently, matching
the behavior of Discord (Promise.all) and WhatsApp (fire-and-forget).
Benefits:
- Ack reactions (👀) appear immediately, not after queue clears
- Multiple chats can be processed in parallel
- maxConcurrent setting now works correctly for Telegram
- Long-running tool calls no longer block other conversations
