[12.x] Avoid class name conflict

[AhmedAlaa4611]

Description

This PR fixes a class name conflict caused by importing two classes with the same name:

• App\Contracts\Repository
• Illuminate\Contracts\Cache\Repository

Since both share the same base name (Repository), PHP throws the following error:

Cannot use Illuminate\Contracts\Cache\Repository as Repository because the name is already in use

To resolve this, I updated the constructor to use a custom UserRepository interface in place of the generic Repository contract from our app domain. This makes the intent clearer and avoids naming collisions.