feat: add Avenger hourly CI fixer workflow

[Copilot]

Adds an hourly Claude-powered agentic workflow ("Avenger") that automatically fixes common mechanical build failures on main and opens a PR with the fixes.

Behavior

• Early exit: A pre-flight check_ci_status job inspects the last completed CI run on main; the agent job is skipped entirely when CI is green
• Repair sequence (only when CI is failing):
  1. git merge origin/main — sync with latest main before any changes
  2. make recompile — only when *.md workflow files changed; aborts if >50 files are produced
  3. make fmt → make update-wasm-golden → make lint → make test-unit
• Creates a [avenger]-prefixed PR with fixes; expires in 2 days
• .github/workflows/** is unconditionally excluded from the patch via excluded-files — the directory is branch-protected and must never appear in agent-created PRs

Key config

safe-outputs:
  create-pull-request:
    expires: 2d
    title-prefix: "[avenger] "
    excluded-files:
      - ".github/workflows/**"

Compiled with gh aw compile avenger --approve; new secrets (ANTHROPIC_API_KEY, OTLP endpoints) are the same set used by other Claude+OTLP workflows in this repo.

[Copilot]

Pull request overview

Adds a new scheduled Agentic Workflow (“Avenger”) intended to run hourly, detect whether main’s CI is failing, and (only when failing) attempt a standardized repair sequence and open a PR with fixes (with .github/workflows/** excluded via safe-outputs).

Changes:

• Introduces avenger.md workflow definition with an early-exit check_ci_status gate and a prescribed repair/runbook for the agent.
• Adds the compiled GitHub Actions workflow avenger.lock.yml (safe-outputs PR creation, OTLP wiring, agent execution, threat detection, and conclusion handling).

Show a summary per file

File	Description
.github/workflows/avenger.md	New Avenger workflow definition + agent runbook (CI status gate, repair steps, safe-outputs configuration).
.github/workflows/avenger.lock.yml	Generated compiled workflow implementing the Avenger automation in GitHub Actions.

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• Files reviewed: 2/2 changed files
• Comments generated: 4