Remove unused UserLevelEnum (dead code)

[jbrooksuk]

Priority: P3 (Medium - Plan to Fix)

Problem

UserLevelEnum (src/Enums/UserLevelEnum.php) defines admin = 1 and user = 2, but the User model uses a boolean is_admin column instead. No code references this enum outside its own file.

Suggested Fix

Delete UserLevelEnum.php. The boolean is_admin approach is simpler and already works.