Remove duplicate password hashing functions in auth_service.py

Problem

app/services/auth_service.py contains its own pwd_context, verify_password(), and get_password_hash() — duplicating what already exists in app/utils/password_utils.py.

Two implementations of the same bcrypt wrapper increases the risk of divergence and makes it unclear which is canonical.

Location

• Duplicates: app/services/auth_service.py lines ~17–20
• Canonical: app/utils/password_utils.py

Fix

Remove the duplicate definitions from auth_service.py and import from password_utils.py instead.

Effort

Low (~30 min)