From test-gauri into demo_branch

Summary by Bito

This pull request implements critical bug fixes in the Book model and D language file, resolving syntax errors, type mismatches, and logical issues. The changes fix function implementations and class methods that previously caused infinite recursion, flawed sorting, and performance issues. The update also addresses incorrect variable types, misspelled enums, and improper memory management while enhancing authentication and chat services for improved role management and websocket handling.