Workshop Builder: persist status issue and append per-run action history

[Copilot]

Workshop Builder currently decides actions (dispatch/modify/suggest/noop) but does not maintain a durable, human-readable execution history. This PR updates the workflow to keep a single status issue and append a run log entry on every execution.

• Persistent status issue lifecycle

  • Introduces status_issue_number in persisted builder state.
  • Adds discovery/rehydration logic for an existing open issue titled [workshop-builder] Workshop Builder status history.
  • Creates the status issue when absent and stores the created reference for subsequent runs.

• Per-run history publication

  • Adds add-comment safe output and uses it to append one status comment per run.
  • Comment payload includes: run timestamp, selected action, target, reason, and latest run-history context.
  • Applies to all outcomes, including noop and focus=status.

• Safe-output and orchestration updates

  • Expands safe outputs to support both status-issue bootstrap and normal suggestion flow (create-issue max increased to 2).
  • Extends workflow instructions with an explicit status-issue maintenance phase after action selection/state updates.
  • Regenerates the compiled lock file to reflect the updated source workflow contract.

safe-outputs:
  create-issue:
    title-prefix: "[workshop-builder] "
    labels: [workshop, automation]
    deduplicate-by-title: true
    max: 2
  add-comment:
    max: 1