Compare and update profile only with new data in /update-profile route

Currently, the /update-profile route does not check for existing data before updating the user profile. Implement logic to compare incoming data with the existing profile, ensuring that only new or changed information is updated.

Find the /update-profile route handler, likely in a file like routes/profile.py or similar. Compare the incoming request data with the current user profile data from the database (Firestore). Update only the fields that are different. Check for existing tests for profile updates or write a simple test to verify the new behavior.

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