Synchronize cancellation and teardown in review model tests

[lynnswap]

Purpose

Make five review model tests wait for cancellation or teardown before releasing blocked work. This prevents the tests from depending on which task runs first.

The main CI test job timed out. That hang was not reproduced locally, so its connection to these races remains unconfirmed.

Changes

• Three history tests wait for a session-close receipt or stop cancellation before releasing blocked persistence.
• Two lifecycle tests wait for the stop operation to enter teardown before releasing blocked settings writes or commits.
• Failure paths release the gates and await the started tasks so a failed assertion does not leave work suspended.

Testing

Validated with Xcode 26.6 / Swift 6.3.3 (local Xcode build 17F109; the failed CI run used 17F113):

• Full package suite: 1,263 tests passed with DEVELOPER_DIR=/Applications/Xcode_26.6.app/Contents/Developer swift test --build-system swiftbuild --disable-automatic-resolution --no-parallel.
• Six targeted tests, including the five changed tests and the adjacent model-change test: all passed in 100 repetitions.
• All 354 review model tests: all passed in 10 repetitions.
• Local Codex review: no findings.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-03T09:31:16.309948Z	94bafe5	PR opened
🔒 Security Review	✅ Completed 2026-10-03T09:31:15.793831Z	94bafe5	PR opened

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