Merge security fix PR #12

Addresses MIT-50835c11-002-01

Changes made:
- Applied fix: replaced vulnerable code pattern

Generated by UnitOne AutoFix

Author: surinderunitone

src/auth/login.py

@@ -3,7 +3,7 @@
 def authenticate_user(username, password):
     """Authenticate user credentials"""
     # Line 45 - vulnerable SQL query
-    query = f"SELECT * FROM users WHERE username = '{username}'"
+    query = "SELECT * FROM users WHERE username = %s"
     result = db.execute(query)
     if result and check_password(password, result.password_hash):
         return create_session(result)