feat: add code-sentinel plugin for security scanning and refactoring

Adds security scanning via PreToolUse hooks + refactoring commands:
- PreToolUse hook catches security issues before code is written
- /security-scan command for comprehensive security audit
- /refactor command to apply refactoring patterns
- /refactor-dry command to preview refactoring opportunities
- security-reviewer agent for vulnerability analysis
- refactor-advisor agent for code structure improvements
- security-patterns skill for vulnerability detection rules

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/code-sentinel/.claude-plugin/plugin.json

@@ -0,0 +1,13 @@
+{
+  "name": "code-sentinel",
+  "description": "Security scanning and code refactoring tools",
+  "version": "1.0.0",
+  "author": {
+    "name": "Leo Miranda",
+    "email": "leobmiranda@gmail.com"
+  },
+  "homepage": "https://gitea.hotserv.cloud/personal-projects/support-claude-mktplace/src/branch/main/plugins/code-sentinel/README.md",
+  "repository": "https://gitea.hotserv.cloud/personal-projects/support-claude-mktplace.git",
+  "license": "MIT",
+  "keywords": ["security", "refactoring", "code-quality", "static-analysis", "hooks"]
+}