Fix skill directory discovery

[matthewp]

Summary

• stop passing raw skill directory paths to Flue createAgent({ skills })
• rely on Flue workspace discovery for repo-local .agents/skills/<name>/SKILL.md
• update the integration regression test to use a repo-like temp cwd with .agents/skills/triage
• rebuild bundled action output

Fixes

Fixes the failure reproduced in #7:

Error: [flue] createAgent() and init() skills[0] must be a skill definition object.

Testing

• pnpm test
• pnpm lint