1. daemon: use $WORKTREES_DIR instead of $HOME/.kugetsu-worktrees
- Worktrees are created in ~/.kugetsu/worktrees but daemon was checking ~/.kugetsu-worktrees
- This caused cmd_start to be called when cmd_continue should have been
2. load_agent_env: add fallback to pm-agent.env
- When dev.env and default.env don't exist, fallback to pm-agent.env
- Ensures GITEA_TOKEN is available
3. Remove '&& disown' pattern that causes 'no such job' errors
- nohup already makes process immune to SIGHUP
- disown was causing errors because job context was lost