Keep complete draft CI when an unchanged pull request is promoted #447

🤖 Generated by the Agentic Engineer

Problem and evidence

Promoting an unchanged draft restarts the complete catalogue suite. Runs 37200572504 and 37204431940 tested the identical source revision and produced the same 233 job-name/outcome pairs: 157 passed and 76 skipped. The second run consumed another 88 minutes without adding validation coverage.

Proposed outcome

Remove only the catalogue's promotion event. Preserve source-change and title/body-edit validation and the separate draft-sensitive auto-merge workflow. Promotion must continue to use the same candidate's complete existing CI results.

Acceptance criteria

• Draft opening and source changes still trigger full catalogue validation; title/body edits retain current protection.
• Promotion alone does not schedule another catalogue run or change test coverage.
• A regression rejects draft-sensitive coverage gates in the catalogue and preserves the separate auto-merge promotion event.
• Observe native before/after promotion at an unchanged candidate and verify required checks still merge normally.

Part of #250. This does not solve the trusted edit-enforcement requirements in #413. Size: S.