Answer one named bot at a time.

[im-ian]

Summary

• A message that names several bots now starts one turn at a time, in the order the names were written. In a 1:1 the current bot answers first, then each mentioned teammate. In a channel, named members go in mention order, and @everyone follows the member list.
• A crew tell from a bot that is still answering waits until that bot is idle. A stop, or a newer message to that bot, drops the bots that have not started. A newer channel post drops the not-yet-started answers for that room.
• The next bot is armed before its followers are visible, so a turn ending in that window cannot start the follower early. A new chain stays ahead of work already queued on that bot. A tell that races a stop is dropped instead of sitting on an idle agent.

cargo test -p crew --bin crew: 222 passed.

Test plan

• In a channel, @A @B @C answers A, then B, then C, and each later bot sees the previous reply.
• @everyone follows member order, one at a time.
• In a 1:1 with A, mentioning only @B answers A, then B.
• Stopping A drops B and C. A newer message to A replaces the pending chain.
• A crew tell sent while A is still answering runs after A is idle, not during A's turn.