Detect sample MCP config drift

[Conalh]

Summary

• Add a separate advisory MCP sample/template/disabled config pass so copied examples are not reported as active server drift.
• Flag risky sample configs separately for unpinned commands and remote endpoints.
• Materialize dynamically discovered sample config paths in git-mode snapshots so the GitHub Action sees nested examples.
• Add detector and git-diff coverage for nested .mcp.json.sample behavior.

Closes #26

Validation

• npm run build
• npm test
• git diff --check