fix(lint): the hand-judged clippy sites in library code

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

crates/sylpheed-export/examples/dialog_rows.rs

@@ -60,7 +60,7 @@ fn main() {
             if rows.is_empty() {
                 continue;
             }
-            rows.sort_by(|a, b| a.1.cmp(&b.1));
+            rows.sort_by_key(|r| r.1);
             let ys: Vec<i32> = rows.iter().map(|r| r.1).collect();
             let gaps: Vec<i32> = ys.windows(2).map(|w| w[1] - w[0]).collect();
             if rows.len() == 4

crates/sylpheed-export/examples/record_population.rs

@@ -33,7 +33,7 @@ fn main() {
             let Some(b) = ui_layout::parse_build(&by) else {
                 continue;
             };
-            for (_, &(o, s)) in &b.records {
+            for &(o, s) in b.records.values() {
                 records += 1;
                 if o + 12 > by.len() || o + s > by.len() {
                     continue;