docs: update usage and clean clippy warnings

src/normalize.rs

@@ -58,7 +58,7 @@ fn normalize_threads(comments: Vec<ReviewCommentDto>) -> Vec<CommentThread> {
     grouped
         .into_iter()
         .map(|(thread_id, mut group)| {
-            group.sort_by(|a, b| comment_sort_key(a).cmp(&comment_sort_key(b)));
+            group.sort_by_key(comment_sort_key);
 
             let root = group.remove(0);
             let file_path = root

src/render/markdown.rs

@@ -64,7 +64,7 @@ pub fn render_markdown(doc: &PrReviewDocument) -> String {
         "- merged at: {}\n",
         doc.meta.merged_at.as_deref().unwrap_or("null")
     ));
-    out.push_str("\n");
+    out.push('\n');
 
     out.push_str("## Commits\n\n");
     for commit in &doc.commits {
@@ -73,7 +73,7 @@ pub fn render_markdown(doc: &PrReviewDocument) -> String {
             commit.short_sha, commit.title, commit.author, commit.date
         ));
     }
-    out.push_str("\n");
+    out.push('\n');
 
     out.push_str("## Diff Stat\n\n");
     out.push_str(&format!(
@@ -86,7 +86,7 @@ pub fn render_markdown(doc: &PrReviewDocument) -> String {
             file.path, file.additions, file.deletions
         ));
     }
-    out.push_str("\n");
+    out.push('\n');
 
     for (review_index, review) in doc.reviews.iter().enumerate() {
         out.push_str(&format!(