Remove unused SQL queries and update email template handling

- Deleted multiple unused SQL query files from the cms-service.
- Refactored email template handling in the cms-service to improve clarity and maintainability.
- Updated environment variable loading in both cms-service and lms-service to use dotenvy for better configuration management.
- Added a new .env.dev file for local development with database and SMTP configurations.
- Set default value for `certificates_enabled` in the shared common models.

services/lms-service/src/main.rs

@@ -35,7 +35,7 @@ use utoipa::OpenApi;
 
 #[tokio::main]
 async fn main() {
-    dotenv().ok();
+    dotenvy::from_filename(".env.dev").or_else(|_| dotenv()).ok();
     tracing_subscriber::fmt::init();
 
     let db_url = env::var("DATABASE_URL").expect("DATABASE_URL debe estar configurada");