status property is source of truth for task state

- Refresh references after merge conflict resolution - Support editor commands in merge conflicts - Make status authoritative for lifecycle - Add abandon and queue-aware reopen - Add tsk open command - Open editor for task body conflicts - Test assign queue picker - Write task conflict markers on pull - Document queue create pull flag - Allow changing queue can-pull - Fold fix-up repairs into clean - Support non-interactive task body edits - Extract queue index mutation helper - Extract HTML rendering helpers - Extract run result error handling - Extract command output row helpers - Document list id-only flag - Add NixOS module for tsk-serv