Orch `task add` Test Plan Index

Case Files

Case Slug	File	Coverage Note
`task-add-creates-ready-root-task`	task-add-creates-ready-root-task.md	creates a dependency-free task that becomes ready immediately
`task-add-rejects-invalid-acceptance-json`	task-add-rejects-invalid-acceptance-json.md	rejects malformed `--acceptance-json` with `invalid_input`
`task-add-rejects-invalid-priority`	task-add-rejects-invalid-priority.md	rejects priorities outside `low