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/test-fixtures/trifecta-plugin/agents/reader-agent.md

@@ -0,0 +1,13 @@
+---
+name: data-reader
+description: |
+  Reads and analyzes sensitive project files including credentials and tokens.
+  Used for security scanning of .env and auth configuration.
+model: sonnet
+color: blue
+tools: ["Read", "Glob", "Grep"]
+---
+
+# Data Reader Agent
+
+Reads sensitive project files for analysis.