R-00374 r7: hold Bot.Host Room sockets until chat.event observed

[Go1c]

R-00374 r7 · hold Bot.Host Room sockets until chat.event observed (RM-00011)

• Baseline origin/main: 5ef2f3370d82496b5f6d4e92d8065d4712466c76
• Head: b81e74d3ef2ff5987df92791a607bfe619a1c760
• Independent review: 通过（无 P0 / P1）

Why

R-00376 live8: hook compile green; four rounds ClientTimerManager drain native-kernel/tickFrame ticks 5,10,15, sent=100. Only 1/4 rounds produced 101 Room chat.event. Other three: eventCount=0 after ~90s. Bot.Host Environment.Exit disposed sockets before the host applied ingress.

What

Keep Bot.Host connected after timer-trace.json until the suite observes Room chat.event and writes release.flag. Tick from pending_wire_chat_inputs (Room WS admit), not sent.txt. Do not treat Sleep(400) / early Exit as SUCCESS.

Verify

• dispatcher review-tree cargo: lib 93 / architecture 17 / host 13 / wire 8
• spec-lint OK (reviewer)

Known gaps

• Live 11-scenario not re-run in this PR; dispatcher rebuilds replay and resumes R-00376.
• 11-scenario CI FAILURE is not SUCCESS. MVP C# host policy red is N-13.