Add comprehensive unit tests for Security, UserModel, and Validation utilities

- Implemented SecurityTest to validate token generation, CSRF protection, input sanitization, and rate limiting.
- Created UserModelTest to ensure correct database operations for user management, including creation, updating, banning, and fetching active users.
- Developed ValidationTest to verify input validation and sanitization for user IDs, nicknames, messages, and API requests.
- Introduced Security and Validation utility classes with methods for secure token generation, input sanitization, and comprehensive validation rules.

.gitignore

@@ -1,14 +1,74 @@
-# Built/minified assets
-assets/**/*.min.css
-assets/**/*.min.js
+# Dependencies
+/vendor/
+/node_modules/
 
-# Distribution directory
-assets/dist/
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# Logs and cache
+/logs/
+/cache/
+*.log
+logs/app.log
+logs/*.log
+
+# Test artifacts
+/tests/coverage/
+/tests/results/
+/test-results/
+/coverage.xml
+phpunit.xml.bak
+
+# File-based storage (migrated to database)
+active_viewers.json
+chat_messages.json
+banned_users.json
+*.json.tmp
+*.json.backup
 
 # Temporary files
 *.tmp
-*.bak
-
-# OS-specific files
+*.swp
+*.swo
+*~
 .DS_Store
 Thumbs.db
+
+# IDE and editor files
+.vscode/
+.idea/
+*.sublime-project
+*.sublime-workspace
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+
+# Backup files
+*.backup
+*.bak
+*~
+*.orig
+
+# Documentation artifacts
+/docs/phpdoc/
+
+# Docker (if used)
+.dockerignore
+docker-compose.override.yml
+
+# Sensitive files
+config/production.php
+config/staging.php
+*.key
+*.pem
+
+# Migration backups
+migrations/*.migrated