Separate domain entities from API DTOs to prevent data leakage and improve API design

[Thiagooms]

Currently, the application exposes domain entities directly in REST API endpoints. This approach has several drawbacks:

Examples of current issues:

• UserController returns the User entity directly, exposing the password hash and internal fields.
• BlogController uses the Blog entity for both the request and response, making it difficult to customize the API format.
• No distinction between create/update/response representations.

assign me this task please @Prathamesh-007

[NyorJa]

please assign this to me