Add governed-runner facade alias

[mdheller]

Summary

Adds prophet governed-runner ... as a product-facing alias for the existing prophet agentplane ... facade, both delegating to the AgentPlane-owned sp-run command.

This preserves the implementation boundary:

• SocioProphet/agentplane owns governed-runner logic and sp-run.
• SocioProphet/prophet-cli exposes stable operator-facing command names.

Adds

• governed-runner parser branch in src/prophet_cli/cli.py
• shared helper for sp-run delegated command surfaces
• tests for:
  • prophet governed-runner doctor
  • prophet governed-runner dossier <run_dir>
  • prophet governed-runner validate-dossier <dossier.json>
  • missing sp-run under the alias returns 127
• README delegation table and examples for both agentplane and governed-runner

Commands

prophet governed-runner doctor
prophet governed-runner preflight ./governed-run-contract.json
prophet governed-runner admit ./governed-run-contract.json --preflight ./preflight-receipt.json --authority-state ./agent-authority-current-state.json --projected-cost-usd 0.25
prophet governed-runner dossier ./.socioprophet/runs/governed-run-alpha-001
prophet governed-runner validate-dossier ./run-dossier.json

Boundary

prophet governed-runner ... is only a product-facing alias over sp-run .... No governed-runner implementation moves into prophet-cli.

Validation

pytest -q