feat(harness): add Cursor Agent CLI adapter

[abojja9]

Summary

• add Cursor Agent CLI as a verified crewmate and scout harness with trust, Run Everything autonomy, explicit workspace, and model propagation
• support all six Cursor Grok 4.5 low, medium, high, and fast model ids through the existing model axis while omitting a separate effort flag
• keep busy state explicitly unknown until a semantic Cursor lifecycle source is verified, and refuse local and remote Cursor Secondmates with an actionable error
• document Cursor detection, workspace behavior, model discovery, and the distinction from the xAI Grok Build harness

Validation

• tests/fm-spawn-dispatch-profile.test.sh
• tests/fm-busy-state.test.sh
• tests/fm-bootstrap.test.sh
• tests/fm-secondmate-harness.test.sh
• bin/fm-lint.sh
• bin/fm-doc-audience-check.sh
• git diff --check

[kunchenguid]

Speaking as Kun's firstmate: closing this as stale. It has been waiting on a contributor update for 14+ days with no author push or comment. Reopen if you want to pick it back up.