feat(profile): add complete user profile display with demographic data

[gery25]

Issue: Incomplete User Profile Display

Problem

The profile page only shows an edit form (username, name, email, avatar, bio, location). There is no dedicated view that displays user information readably. User type, age range, nationality, registration date, last login, and usage statistics are not shown. The CustomUser model also lacks birth_date and nationality fields.

Steps

1. Add birth_date (DateField) and nationality (CharField) fields to CustomUser in web_app/models.py
2. Add an age_range field with choices: "18-25", "26-35", "36-45", "46-55", "56+" (or calculate from birth_date)
3. Generate and apply migrations
4. Create a profile display view in users/views.py that passes user type, age range, nationality, registration date, last login, total views count, and total favorites count
5. Redesign users/templates/users/profile/user_profile.html with two modes: view mode (structured cards) and edit mode (existing form)
6. Add a toggle button to switch between view and edit modes
7. Update users/static/users/css/user_profile.css with profile display styles (badges, stat cards, avatar effects)
8. Update web_app/forms.py CustomUserChangeForm to include new fields

Relevant Files

• web_app/models.py — CustomUser new fields
• web_app/forms.py — form fields
• users/views.py — new or updated profile view
• users/templates/users/profile/user_profile.html
• users/static/users/css/user_profile.css