[darxnet]

Three routing/FSM bugs found while checking the issues competitors fixed this week (aiogram#1997, go-telegram/bot#304, node-telegram-bot-api#1382, python-telegram-bot#5398).

Changes

• Commands for other bots. /start@other_bot no longer reaches HandleCommand, FilterCommand or ctx.Command(): in a group with several bots, an admin bot (or one with privacy mode off) answered commands meant for the others. The username comes from Client.Me, fetched once on the first @-addressed command; if getMe fails, the command is accepted as before. A command for another bot is an ordinary message for this one (HandleOnMessage still sees it).
• Line breaks. A command ends at any whitespace, so /start\npayload is routed to /start; Message.Payload and CallbackQuery.Payload split at a line break or tab, as Args already did.
• FSM key for messages sent on behalf of a chat. Anonymous group admins, users writing as a channel and automatic forwards all arrive from one service user (GroupAnonymousBot, Channel_Bot), so every such sender shared one state. The state is now keyed by sender_chat; callback queries keep the presser's id. States previously stored under those service users are no longer found.
• FuzzEntityText guards EntityText against out-of-range entity offsets and lengths (2.6M execs, no panic).

Checked and left as is: the per-chat Throttle waits before the global WithRPS token is taken in the transport, so throttled chats do not consume global slots (the node-telegram-bot-api#1390 bug).

Testing

make lint and make test pass locally; new tests in addressing_test.go, the existing @bot tests now use a canned getMe instead of the network.