User module | Register Feature

# User Create Process

### User Story

- Upon inputting a valid username, email, and password, the system processes the data, establishes a new user account, and presents a success message to confirm the registration.
- Upon inputting invalid data, the system displays error messages and prompts the user to provide correct and complete information for successful registration.

### Task

- [x] Implement Data Access Object (DAO) Layer.
- [x] Implement Service Layer.
- [x] Create JUnit Test Cases.
- [x] Ensure that the test cases are passing.
- [ ] Write clear and concise comments in the code to explain complex logic.

### DAO
- [createUser()

Service
- registerUser()

### Service Test
TestRegisterFeature
- testRegistrationSuccess()
- testRegistrationFailure()

### Estimation
- 3hours

# Flowchart

```mermaid
flowchart TD
A[Start]
B[Display Registration Form]
C[User Fills out Form]
D[Validate Input]
E{Validation Successful?}
F[Save User Data]
G[Registration Successful]
H[Display Error Messages]
I[End]
A --> B
B --> C
C --> D
D --> E
E -- Yes --> F
F --> G
E -- No --> H
H --> B
H --> I
G --> I
```