- migration 012: cja_changelog.actor column
- seed-changelog: optional 5th 'by' element (defaults to Carlos Arias);
display shows 'Added · time · by <actor>'
- changelog skill documents the actor field + attribution logic (agents name
themselves, human/CLI edits are Carlos Arias)
- Web Designer prompt now logs each change to the changelog via the skill,
attributed to 'Website Designer Agent'; runner reseeds cja_changelog when the
seed file changed (the agent has no shell)
