Login API

Endpoint: /auth/login
Method: POST
Description: Authenticates a user and sends an OTP to the user's phone.

Request Body:

{
  "phone": "string",
  "backend_secret": "string"
}

Responses:

200 OK
```
{ "message": "OTP sent" }
```
401 Unauthorized
```
{ "message": "Unauthorized" }
```

Example:

curl -X POST http://<your-server-address>/auth/login \
-H "Content-Type: application/json" \
-d '{"phone": "1234567890", "backend_secret": "your_backend_secret"}'

Getuserdetails Register