Comment posting is idempotent + tests

src/routes/posts.rs

@@ -151,9 +151,11 @@ pub async fn see_post(
         let comments = get_comments_page_for_post(&connection_pool, post_id, 1)
             .await
             .context("Failed to fetch latest comments")?;
+        let idempotency_key = Uuid::new_v4().to_string();
         let template = HtmlTemplate(PostTemplate {
             post,
             comments,
+            idempotency_key,
             current_page,
             max_page,
             comments_count,