ci: dispatch-only always-failing workflow — real-GitHub fixture for #487

[mabry1985]

Refs #487.

A dispatch-only workflow with one job that fails on purpose. It's the real-GitHub fixture for #487's rerun_failed_ci seam: rerun a PR's failed Actions jobs once before spending a coder fix round on what may be a flake.

• The external-seam ratchet requires every gh seam to be exercised against real GitHub, and gh run rerun --failed needs a run that actually failed.
• It lives in this repo, not a separate one, because the real tier authenticates with this repo's GITHUB_TOKEN, which can't rerun another repository's jobs without a stored personal access token. This mirrors the permanent fixture PR, PB_GH_FIXTURE_PR → ⚠️ CI FIXTURE — DO NOT MERGE, DO NOT CLOSE #370.
• After merge: dispatch it once and pin the failed run id in the repo variable PB_GH_FIXTURE_FAILED_RUN.
• It never runs on push or PR, and each rerun costs one ~5s job.

🤖 Generated with Claude Code

[protoreview]

QA panel review — PASS

code-review-structural · head 9063a4d5fc1a · formal

The PR adds a single dispatch-only GitHub Actions workflow (ci-fixture-fails.yml) that always fails by design, serving as a fixture for a future worktree.rerun_failed_ci seam. No findings were raised, so there was nothing to verify. The file is well-formed, minimal in permissions, self-documenting, and introduces no cross-file drift. No action required.

No findings — the review came back clean.

findings JSON (machine-readable)

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[protoreview]

Promoting the PASS verdict for head 9063a4d5fc1a: all checks terminal-green, zero unresolved review threads. (approve-on-green)