User Module

## Description
Develop the backend functionalities for user management.

### Tasks
- [x] #1
- [x] #2
- [x] #3
- [x] #4

### Attributes:
- [x] userId
- [x] email
- [x] password
- [x] name
- [x] phone number
- [x] type
- [x] isDeleted

### Validations:
- [x] validateUser()
- [x] validateName()
- [x] validateEmail()
- [x] validatePassword()
- [x] validatePhonenumber()
- [x] validateDeleteUser()

### Test:
- [x] testValidateUser()
- [x] testValidateEmail()
- [x] testValidatePassword()
- [x] testValidatePhonenumber()
- [x] testValidateName()

The issue names a user-management backend and validation targets—validateUser(), validateName(), validateEmail(), validatePassword(), validatePhonenumber(), validateDeleteUser(), and their tests—but gives no file paths or entry points. First locate those symbols and the existing user module, then compare the implementation with the listed attributes and confirm every named validation test passes.

Written by the indexing model from the issue text.