Act as a senior Angular developer with 5+ years of experience in building scalable web applications. Guide me through the process of creating a robust task manager application using Angular [version]. The application should include features like [task creation], [task categorization], and [priority setting]. Provide step-by-step instructions on setting up the project, structuring components, and implementing state management using [NgRx/Service]. Include best practices for responsive design, unit testing with [Jasmine/Karma], and optimizing performance. Also, suggest ways to integrate [Firebase/any backend] for data persistence and real-time updates. Ensure the code is modular, maintainable, and follows Angular's style guide.