Complete basic user management

[adityashibu]

This pull request includes several changes across multiple files to enhance user management, improve security, and update the frontend to reflect backend changes. The most important changes include adding user selection functionality, updating CORS settings, and integrating real-time updates with Firestore.

Backend Changes:

• backend/fastAPI.py: Added endpoints to set and get the selected user, and updated the /updates endpoint to return combined updates from devices and users. [1] [2] [3] [4]
• backend/users.py: Implemented functions to select a user, get the selected user, and retrieve updates. Added persistence for the selected user in a JSON file.

Frontend Changes:

• frontend/src/app/ui/dashboard/accountMenu.jsx: Updated the account menu to fetch and display the selected user from the backend. [1] [2] [3] [4]
• frontend/src/app/users/page.jsx: Modified the user login process to set the selected user upon successful login and redirect to the dashboard. [1] [2]

Security Improvements:

• database/users_db.py: Added password hashing using bcrypt and updated Firestore synchronization logic to handle user data securely.

Configuration Updates:

• backend/.gitignore: Added selected_user.json to the .gitignore file to exclude it from version control.

[david-g-f]

Works