[WRONG BRANCH] fix(lab): ensure manual Lab runs are cancellable during shutdown

[luvs01]

Motivation

• Prevent manual /api/lab/automation/run executions from continuing past drainAndShutdown when Lab was never activated, by ensuring manual runs register a shutdown hook so they are cancelled like other Lab activities.

Description

• Register a run-scoped optional shutdown hook for manual dispatches in src/lab/automation/orchestrator.ts using registerOptionalShutdownHook(...) and detach it in a finally block so the hook cannot leak after completion.
• Add an outcome-level regression test in tests/lab-automation-review-regressions.test.ts that starts a manual run, releases the activation lease, invokes runOptionalShutdownHooks(), and asserts the manual run is cancelled.
• Reset optional-shutdown-hooks in the test teardown to avoid cross-test leakage.

Testing

• Ran git diff --check and created the fix commit (fix(lab): cancel manual runs during shutdown).
• Ran bun run typecheck (local run) which completed without type errors for the edited modules.
• Executed the focused test run bun test tests/lab-automation-review-regressions.test.ts, which failed during module load with a Bun/runtime node:zlib export incompatibility (zstdDecompressSync) unrelated to this change; the failure prevented the full focused-suite execution in this environment.
• tests/optional-shutdown-hooks.test.ts (focused) was not fully exercised due to the prior runtime error; the new tests exercise the optional-shutdown-hooks path and were authored alongside the fix.

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📥 Commits

Reviewing files that changed from the base of the PR and between 161c09f and 37b3d5b.

📒 Files selected for processing (2)

• src/lab/automation/orchestrator.ts
• tests/lab-automation-review-regressions.test.ts

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[github-actions]

✅ Deterministic PR hygiene checks passed.

[github-actions]

⏳ DRAFT

• wrong target branch (main); retarget to dev.

What to do

• Retarget this PR to dev — all contributions go to dev.

Its title has been prefixed with [WRONG BRANCH].
This pull request was already a draft. Its draft status will be preserved after every issue above is resolved.