Feat mcp loop gate

[THRISHAL12345]

Summary

Expose the loop-gate policy checking logic as an MCP resource and tool within mcp-server, allowing MCP-connected agents to mechanically verify their intended changes against the static safety policy directly.

Changes

• New pattern or starter (followed templates/pattern-template.md + updated registry.yaml)
• Doc / example improvement
• Tool change (mcp-server & loop-gate)
• Story (includes real failure or surprise + lesson)

Checklist (from CONTRIBUTING)

• All required sections present for patterns
• Links work from README, patterns/README, starters/README, docs/index
• No secrets, tokens, internal company URLs
• STATE.md* examples use .example suffix
• Safety-related content references docs/safety.md
• Ran node tools/loop-audit/dist/cli.js . (or on the starter) and addressed findings

Testing / Dogfood

• Added and passed new integration tests for gate resource and loop_gate_check tool in mcp-server/test/server.test.mjs.
• npm test runs cleanly across the repository.

Screenshots / Examples (if UI or command output)

Agents can now query loop://gate and call loop_gate_check(action: 'commit', paths: ['...']) without needing bash execution capabilities.