feat: support items data saved to backend

[MaxWutw]

This pull request refines how profile updates are handled in the patch method of game_data/views.py. The main focus is on optimizing database updates by specifying only the fields that have changed, rather than saving the entire profile or unrelated fields. This helps improve performance and data integrity.

Optimized profile updates:

• The profile.save() call in the main patch flow now uses the update_fields parameter to only update relevant fields, reducing unnecessary database writes.
• In the inventory update section, the update_fields list is dynamically built to include only the fields that were actually changed, ensuring only modified fields are saved.

Code cleanup and simplification:

• Removed redundant loops that set profile fields multiple times, simplifying the update logic for profile attributes.