Task is to refactor the **domain and data layers** of an existing feature so that they fully comply with the architecture rules defined in:

* `apps/mobile/docs/01-architecture-principles.md`

## 📍 TARGET FEATURE

Feature to refactor:

```
apps/mobile/packages/features/staff/payments
```

Files exist in:

```
lib/src/domain/
lib/src/data/
```

## 🏆 GOLD STANDARD REFERENCE

Use the following feature as the **gold standard implementation** for structure, responsibility split, and dependency direction:

```
apps/mobile/packages/features/staff/authentication
```

Follow its patterns for:

* Repository interfaces
* Use case design
* Data layer delegation
* Interaction with `apps/mobile/packages/data_connect`

## 🎯 GOAL

Refactor the feature so that its **Domain** and **Data** layers strictly follow **KROW Clean Architecture** as defined in `apps/mobile/docs/01-architecture-principles.md`.

The feature must rely on **shared Domain entities** and must delegate all data access through `apps/mobile/packages/data_connect`.

## STRICT RULES (NON-NEGOTIABLE)

You MUST follow **all rules defined in**:

* `apps/mobile/docs/01-architecture-principles.md`

In particular, ensure that:

* Domain uses **only entities from**:

  ```
  apps/mobile/packages/domain/lib/src/entities
  ```
* Feature-level domain models are removed
* Repository interfaces live in the Domain layer
* Repository implementations live in the Data layer
* Domain does NOT return concrete data objects
* Usecases in the domain layer must be extended from the `apps/mobile/packages/core/lib/src/domain/usecases/usecase.dart`.
  * If there are arguments in the usecases, they must be extended from the `apps/mobile/packages/core/lib/src/domain/arguments/usecase_argument.dart`. Example usecase is given below
    - `apps/mobile/packages/features/staff/authentication/lib/src/domain/usecases/verify_otp_usecase.dart`
* Data layer does NOT contain business logic and not create objects only call the `apps/mobile/packages/data_connect`.
* All data access flows through `apps/mobile/packages/data_connect`

## DOCUMENTATION

* Add clear **doc comments** to all files you modify
* Document:
  * Purpose of the file
  * Role of the class or interface in the architecture

## SAFETY GUARANTEES

* Do NOT change existing behavior
* Do NOT break presentation layer contracts
* Do NOT bypass `apps/mobile/packages/data_connect`

## EXPECTED OUTPUT

* Domain layer aligned with `apps/mobile/docs/01-architecture-principles.md`
* Data layer aligned with `apps/mobile/docs/01-architecture-principles.md`
* Structure and patterns consistent with:

  ```
  apps/mobile/packages/features/staff/authentication
  ```
* Clean, documented, and compliant implementation

Proceed with the refactor now.