Constant MODELS 

pub const MODELS: &str = r#"use chrono::{DateTime, Utc};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// Database entity struct
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct UserEntity {
    pub id: Uuid,
    pub username: String,
    pub email: String,
    pub password: String,
    pub created_at: DateTime<Utc>,
}

/// DTO with password included
#[derive(Debug, Serialize, Deserialize, JsonSchema, Clone)]
pub struct User {
    pub id: String,
    pub username: String,
    pub email: String,
    pub password: String,
    pub created_at: String,
}

/// DTO without password
#[derive(Debug, Serialize, Deserialize, JsonSchema, Clone)]
pub struct UserInfo {
    pub id: String,
    pub username: String,
    pub email: String,
    pub created_at: String,
}

#[derive(Debug, Serialize, Deserialize, JsonSchema, Clone)]
pub struct LoginCredentials {
    pub email: String,
    pub password: String,
}

#[derive(Debug, Serialize, Deserialize, JsonSchema, Clone)]
pub struct RegistrationCredentials {
    pub username: String,
    pub email: String,
    pub password: String,
}

#[derive(Debug, Deserialize, Serialize)]
pub struct SuccessResponse {
    pub status: u16,
    pub message: String,
}

#[derive(Debug, Deserialize, Serialize)]
pub struct ErrorResponse {
    pub status: u16,
    pub message: String,
}
"#;