ci: add sync-skills workflow

[ko3n1g]

Summary

• Adds sync-skills.yml workflow to keep skills/ in sync with agent directories via the _sync_skills.yml@v0.91.0 reusable workflow
• Removes stale skills/.claude directory
• Adds Git & PR conventions section to AGENTS.md so agents know to use type(scope)?: description format for commit messages and PR titles (prevents bracket-prefix anti-patterns like [ci] fix: …)

Test plan

• CI passes
• Skills sync correctly on next push to main

[akoumpa]

Hi @ko3n1g , thanks for making this.

Initially, i used the .claude/skills so that claude would find them out of the box, however, this created problem, because people mount their skills on .claude/skills and then git was causing issues, thus reverted back to using skills/.

Do you know if this would introduce any similar conflict?

[ko3n1g]

Hi @ko3n1g , thanks for making this.

Initially, i used the .claude/skills so that claude would find them out of the box, however, this created problem, because people mount their skills on .claude/skills and then git was causing issues, thus reverted back to using skills/.

Do you know if this would introduce any similar conflict?

Yeah I think that would still lead to issues. Perhaps we want to add these folders to .gitignore as a follow-up this PR. We need a single source of truth so that we can symlink it for other agents into read-only dirs