Add an option to generate a React frontend with Register and Signup pages for actor models

Currently, Servitect focuses on server-side functionality and does not provide an option to generate a frontend. To enhance usability and streamline full-stack development, there should be an option to create a React-based frontend.

The proposed frontend should include:

A Register Page and Signup Page.
These pages should dynamically adapt to the number of actor models created in the project, allowing user-specific authentication for each actor model.

The generated React frontend should follow clean code practices and be structured in a modular way, ensuring it aligns with the existing standards of Servitect.

This feature will make Servitect more versatile by offering developers an end-to-end solution for building both backend and frontend in a cohesive manner.

The issue names no files, tests, or entry points. Start by tracing how Servitect generates actor models and where its menu exposes generation options, then determine how the React output should be structured and adapted for each actor model. Done means the generator can produce modular Register and Signup pages with actor-specific authentication.