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/tests/fixtures/supply-chain/yarn-compromised.lock

@@ -0,0 +1,14 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT.
+# yarn lockfile v1
+
+colors@1.4.1:
+  version "1.4.1"
+  resolved "https://registry.yarnpkg.com/colors/-/colors-1.4.1.tgz"
+
+express@^4.18.0:
+  version "4.18.2"
+  resolved "https://registry.yarnpkg.com/express/-/express-4.18.2.tgz"
+
+lodash@^4.17.21:
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz"