Fix v0.7.1 release-validation hang with deterministic failure fixture

[eybersjp]

Problem

The controlled v0.8.1 release reached npm run v071:validate after all preceding release gates passed, then remained alive until the release workflow's 25-minute timeout cancelled the job. No tag or package was published.

Targeted process-isolated diagnostics proved that TEST F was the only failing/hanging regression. The test used OS-specific special paths (Z:\\... on Windows and /proc/... on Linux) to simulate an unwritable project root. The Linux /proc pseudo-filesystem made that failure contract non-deterministic in GitHub Actions.

Fix

• Replace the OS-special-path fixture in TEST F with a portable temporary fixture: create a regular file and attempt to bootstrap beneath it, producing an immediate ENOTDIR/equivalent failure on Windows, Linux, and macOS.
• Consume and verify the Control Center HTML response in TEST K as normal HTTP test hygiene.
• Add the canonical npm run v071:validate gate to normal pull-request CI so this suite is exercised before release time.

Verification

• All TEST A–M regressions passed under isolated diagnostics after the fixture correction.
• The exact monolithic npm run v071:validate command used by the release pipeline now passes in GitHub Actions.
• Full PR CI passes, including skills/agents, plugin sync, documentation, OpenCode, platform adapters, research contract, v0.7.1 regressions, and Autopilot/evaluations.
• Temporary diagnostic runner and speculative Runtime API shutdown change were removed before merge.

Release safety

This does not bypass or weaken the release gate. It makes the existing failure-path test deterministic and moves the same canonical regression suite earlier into PR validation. v0.8.1 will be retried only after this PR is merged.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Fix TEST F before requiring the regression suite in CI

On the Ubuntu/Linux runner configured for this job, this newly required command never completes: v071:validate runs TEST F, where bootstrapProject('/proc/invalid_dir/test') hangs in the recursive fs.mkdirSync call. I verified that TEST K now exits successfully in isolation, but TEST F and the full command time out, so every push and pull request will consume the 15-minute job timeout rather than reaching the remaining validation step. Replace TEST F's /proc fixture with a reliably unwritable, non-hanging fixture before enabling this gate.

AGENTS.md reference: AGENTS.md:L27-L27

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