feat(llm-security-copilot): port llm-security v5.1.0 to GitHub Copilot CLI

Full port of llm-security plugin for internal use on Windows with GitHub
Copilot CLI. Protocol translation layer (copilot-hook-runner.mjs)
normalizes Copilot camelCase I/O to Claude Code snake_case format — all
original hook scripts run unmodified.

- 8 hooks with protocol translation (stdin/stdout/exit code)
- 18 SKILL.md skills (Agent Skills Open Standard)
- 6 .agent.md agent definitions
- 20 scanners + 14 scanner lib modules (unchanged)
- 14 knowledge files (unchanged)
- 39 test files including copilot-port-verify.mjs (17 tests)
- Windows-ready: node:path, os.tmpdir(), process.execPath, no bash

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/llm-security-copilot/knowledge/skill-registry.json

@@ -0,0 +1,7 @@
+{
+  "version": "1",
+  "description": "Seed data for skill signature registry. Known-good entries that ship with the plugin. Entries here are merged into the active registry on first load but never overwrite existing scanned entries.",
+  "updated": "2026-04-03T00:00:00.000Z",
+  "entry_count": 0,
+  "entries": {}
+}