feat: Add initial API infrastructure including tutorial management handlers with CRUD operations and data validation, along with authentication and comments modules.

Author: zerox80

backend/src/auth.rs

@@ -382,7 +382,7 @@ where
 
         // Check if token is blacklisted
         let pool = DbPool::from_ref(state);
-        if db::is_token_blacklisted(&pool, &token)
+        if repositories::token_blacklist::is_token_blacklisted(&pool, &token)
             .await
             .map_err(|e| {
                 tracing::error!("Database error checking token blacklist: {}", e);

backend/src/handlers/comments.rs

@@ -122,7 +122,7 @@ pub async fn list_comments(
             )
         })?;
 
-    if exists.is_none() {
+    if !exists {
         return Err((
             StatusCode::NOT_FOUND,
             Json(ErrorResponse {

backend/src/handlers/tutorials.rs

@@ -554,7 +554,7 @@ pub async fn update_tutorial(
         &color,
         &topics_json,
         &topics_vec,
-        tutorial.version,
+        tutorial.version.try_into().unwrap_or(1),
     )
     .await
     .map_err(|e| {