Code audit for structure and safety

[Mortgy]

This commit addresses multiple critical issues found during code audit:

MEMORY LEAK FIXES:

• Add deinit to MGWebServer to remove NotificationCenter observers
• Invalidate URLSession in stop() and deinit to release resources
• Remove dangerous Utils.repeatTask() function (unstoppable infinite recursion)
• Clear all NetService delegate references in cleanup methods
• Add deinit to BonjourServiceManager and BonjourClientManager
• Set audioPlayer to nil after stopping in AudioPlaybackManager
• Add deinit to AudioPlaybackManager for proper cleanup

SAFETY & SECURITY FIXES:

• Remove all force unwrapping (!):
  • MGWebServer.swift: Safe port number handling
  • HTTPRequest.swift: Safe boundary data encoding
  • Utils.swift: Safe pointer handling in getIPAddress()
• Add path validation to prevent directory traversal attacks in RouteManager
• Add validateAndSanitizePath() to ensure files stay within base directory

THREAD SAFETY:

• Make RouteManager thread-safe with serial DispatchQueue
• Add proper synchronization for routes dictionary access

CRASH PREVENTION:

• Fix recursive receive() in RequestHandler (potential stack overflow)
• Dispatch next receive to queue instead of direct recursion
• Add request size limits (10 MB max) to prevent memory exhaustion
• Add HTTP 413 status code for oversized requests
• Proper connection cleanup to prevent resource leaks

CODE IMPROVEMENTS:

• Add proper [weak self] captures in all closures
• Add connection cleanup tracking in RequestHandler
• Add status codes 403 and 413 to HTTPResponse
• Improve error handling throughout

All critical and high-priority issues from the audit have been resolved.