Add user logout and account deletion functionality

[aj47]

Users currently cannot log out of their accounts or delete their accounts entirely. This is an important feature for user privacy and account management.

Proposed Features:

• Add a logout button/functionality to end user sessions
• Add account deletion option that removes all user data
• Include confirmation dialogs for destructive actions
• Ensure proper cleanup of user data upon deletion

Benefits:

• Improved user privacy and control
• Compliance with data protection regulations
• Better user experience for account management

Implementation Notes:

• Consider adding these features to user settings/profile page
• Ensure proper authentication checks
• Handle any related data cleanup (projects, settings, etc.)