Ln 760 Security Setup

This is a coordinator that runs security scans during project setup by delegating to two workers: a secret scanner (ln-761) and a dependency vulnerability auditor (ln-625). It aggregates their findings, calculates a security score, and generates the infrastructure you need: SECURITY.md, pre-commit hooks, and a GitHub Actions workflow. The workflow is explicit about preserving existing configs rather than clobbering them, and it won't fail if scanning tools are missing. Use this when bootstrapping a new project or adding security infrastructure to an existing one. It's designed to give you a unified view of both leaked secrets and dependency CVEs without making you run separate tools manually.