Pin Matt Pocock Skills Reviewer to an explicit Copilot model

[Copilot]

The Matt Pocock Skills Reviewer workflow was failing at runtime because it relied on Copilot’s default model resolution, which can map to an unsupported model for some subscription tiers. This change removes tier-dependent model selection from that workflow path.

• Problem addressed

  • The workflow’s Copilot invocation resolved COPILOT_MODEL via fallback (default), causing 400 The requested model is not supported in production runs.

• Workflow source update

  • Set an explicit model in .github/workflows/mattpocock-skills-reviewer.md:
    • engine.model: gpt-4.1

• Compiled workflow alignment

  • Regenerated .github/workflows/mattpocock-skills-reviewer.lock.yml so generated runtime env and metadata use the explicit model (no default fallback for this workflow).

engine:
  id: copilot
  model: gpt-4.1
  max-continuations: 6