Update agent control docs and contract metadata

[pengfei-threemoonslab]

Summary

• Update local control guidance to use shipgate check and the expanded agent_result_v1 control fields
• Bump the runtime contract metadata to v4 and add the local agent-result schema path and commands
• Refresh downstream docs, snippets, and adoption harness criteria to reflect Codex, Claude Code, and Cursor flows

Testing

• Not run (not requested)