Harden Workshop Builder to always emit a safe output (noop fallback)

[Copilot]

Workshop Builder runs could complete successfully without producing any safe output, triggering “No Safe Outputs Generated” alerts. This change tightens prompt requirements so every run emits one primary safe output, with noop as the explicit fallback path.

• Prompt contract hardening

  • Added an explicit top-level instruction in workshop-builder.md that every run must emit at least one safe output item.
  • Added a strict fallback rule: if no dispatch/PR/issue action is valid, call noop and do not end with text-only output.

• No-op gate reinforcement

  • Extended the existing “No-op rule” section with an end-of-run re-check:
    • if no safe output has been produced yet, call noop immediately.

• Compiled workflow sync

  • Regenerated workshop-builder.lock.yml to reflect the updated source prompt and keep runtime behavior aligned with the authored workflow.

Before you finish the run, you must emit at least one safe output item. If no
dispatch/PR/issue action is valid, call `noop` with a concise summary of what
you checked and why no action was needed. Never end with text-only output.

Before ending the run, re-check this requirement: if you have not yet produced
one of the safe outputs listed above, call `noop` immediately.

• Fixes [aw] Workshop Builder produced no safe outputs #1649