Fix some more clippy issues

crates/next-code-frame/src/frame.rs

@@ -155,9 +155,13 @@ pub fn render_code_frame(
     }
 
     // Render each line
-    for line_idx in first_line..last_line {
+    for (line_idx, line_content) in lines
+        .into_iter()
+        .enumerate()
+        .take(last_line)
+        .skip(first_line)
+    {
         let line_num = line_idx + 1;
-        let line_content = lines[line_idx];
         let is_error_line = line_idx >= start_line && line_idx <= end_line;
 
         // Apply consistent truncation to all lines in the window

crates/next-code-frame/src/tests.rs

@@ -426,7 +426,7 @@ Another paragraph.
         ..Default::default()
     };
 
-    let result = render_code_frame(&source, &location, &options).unwrap();
+    let result = render_code_frame(source, &location, &options).unwrap();
 
     let expected = r#"  1 | # Title
   2 |