fix(codex): scope app-server lifecycle to each invocation

[GigiTiti-Kai]

Summary

• supervise one Codex app-server per project and invocation scope, then stop only the children owned by that invocation
• route role bridges to the exact scoped server and recorded thread while leaving malformed requests unread
• close the reviewed race after the child lock and cover duplicate-scope and malformed-request boundaries

Verification

• full Bats suite: 1740/1740 passed with AGMSG_CODEX_SHIM_DISABLE unset for the Codex harness
• focused new regressions: 3/3 passed
• Codex bridge launcher suite: 79/79 passed
• Codex monitor suite: 23/23 passed
• resume, delivery, and shim suites: 253/253 passed
• bash -n and git diff --check passed

Local review evidence

• surface/class: Codex standard T2; fresh reviewer stalled twice with no progress events, so the runbook fallback was used
• BASE_SHA: 660f67b
• HEAD_SHA: 14855dd
• structured self-review covered ownership, signal authority, scoped request validation, lock races, peer isolation, cleanup, and test coverage
• P0/P1: none; no findings required a code change
• earlier three-commit read-only review findings were closed by the final commit and its focused regressions