core: rustfmt wraps the chain in the tag-span grammar test

`cargo fmt --all --check`, the only failing gate on d9e5753 — clippy, all 148
tests and every other lane were green. The line was 96 characters, under the
100 max_width, but a chain is held to `chain_width` (60% of it).

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

core/src/local/derive.rs

@@ -520,7 +520,10 @@ mod tests {
     #[test]
     fn tag_spans_agree_with_extract_tags_about_what_a_tag_is() {
         let body = "#1 nope a#b no but #Yes ##no";
-        let names: Vec<String> = extract_tag_spans(body).into_iter().map(|t| t.name).collect();
+        let names: Vec<String> = extract_tag_spans(body)
+            .into_iter()
+            .map(|t| t.name)
+            .collect();
         assert_eq!(names, extract_tags(body));
     }