Deferred review findings from PR #11395: fix(acp): preserve caller-owned mode after child reap

Verified review findings from PR #11395 by qqqys whose fixes lie outside that PR's footprint, deferred by the autofix loop for follow-up. cc @qqqys. Each rc: item links back to its original review comment. A maintainer or the PR author can turn any item into its own issue/PR and apply the ready-for-agent flow to that issue — nothing here is scheduled automatically.

• rc:3972173759 packages/acp-bridge/src/bridge.ts: Verified real: the attach-time snapshot corrections spread the pre-apply modes object, so a stale modes._meta.planExecutionMode survives a correction that moves the session out of plan. Deferred under the round-5+ convergence posture: the fix changes the response payload shape at three correction sites and needs its own witness cycle. — comment
• rc:3972173785 packages/acp-bridge/src/bridge.ts: Verified real: the coalesced-waiter twin of the live-attach snapshot correction has no test distinguishing its two operands (deleting the block leaves the suite green). Deferred: the witness needs the coalesced-restore harness, more setup than fits in this Critical-focused round. — comment
• rc:3972173801 packages/cli/src/serve/server.test.ts: Verified real: no test asserts the load/resume routes forward approvalMode to the bridge. Deferred under the round-5+ convergence posture; pure test addition, no production change needed. — comment