Error handling middleware

Vytvoř error handling middleware pro [FRAMEWORK] API.\n\n**Requirements:**\n\n**1. Error Types:**\n- ValidationError (400)\n- UnauthorizedError (401)\n- ForbiddenError (403)\n- NotFoundError (404)\n- ConflictError (409)\n- ServerError (500)\n\n**2. Error Response Format:**\n```json\n{\n "error": {\n "code": "ERROR_CODE",\n "message": "Human-readable",\n "details": {},\n "timestamp": "ISO",\n "path": "/api/endpoint"\n }\n}\n```\n\n**3. Features:**\n- Logging (different levels)\n- Stack trace (dev only)\n- Error monitoring (Sentry integration)\n- Rate limit errors\n- Graceful degradation\n\n**4. Async error handling**\n\n**Include:**\n- Middleware implementation\n- Custom error classes\n- Usage examples\n- Testing\n\nFramework: [EXPRESS/FASTIFY/NESTJS]. Language: [TS/JS].