mcp-cap: Pinning Changes to the MCP Server's Capability Surface

`mcp-cap` is a DSH plugin designed to address the opacity and potential security risks of MCP server capability declarations. It secures and audits servers by refusing to execute tools and applying the principle of least privilege. Core features include rejecting sensitive operations such as `tools/call`, sealing declared capabilities into a lock file to create an audit record, and detecting capability changes. Once installed, users can inspect, lock, and compare a server’s capability surface through commands such as `inspect`, `seal`, and `verify`. Its exit codes clearly indicate capability changes or upgrades, helping users prevent unauthorized privilege escalation.