- Fix session ID detection in cmd_start to exclude pm_agent_session_id
(prevents forked sessions from getting same ID as pm-agent)
- Add extract_issue_ref_from_message function for parsing issue refs
from short format (git.fbrns.co/user/repo#123) or URLs
- Update cmd_delegate to call cmd_start when issue ref is found
- Pass GITEA_TOKEN to opencode run for API access
- Fixes#81