Format the tree the way the gate asks for it

`cargo fmt --check` is a required step and had drifted across 45 files. Most of
it arrived this week: several operations were written in parallel worktrees and
merged by hand, and a hand-merge resolves conflicts without ever running the
formatter over the result.

No behaviour changes — this is `cargo fmt --all` and nothing else, kept as its
own commit so the next reader can skip it wholesale rather than search it for
one that matters.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/dr-export/src/lib.rs

@@ -250,7 +250,13 @@ mod tests {
 
     #[test]
     fn png_export_produces_a_png() {
-        let out = export(&frame(32, 32), &settings(ExportFormat::Png), "a.png".into(), None).unwrap();
+        let out = export(
+            &frame(32, 32),
+            &settings(ExportFormat::Png),
+            "a.png".into(),
+            None,
+        )
+        .unwrap();
         assert_eq!(&out.bytes[..8], b"\x89PNG\r\n\x1a\n");
     }
 
@@ -270,8 +276,20 @@ mod tests {
     fn a_sixteen_bit_tiff_is_larger_than_an_eight_bit_one() {
         // Both are uncompressed RGB; the only difference is the sample width,
         // so this is what proves the 16-bit path is not quietly writing 8.
-        let eight = export(&frame(16, 16), &settings(ExportFormat::Tiff8), "a".into(), None).unwrap();
-        let sixteen = export(&frame(16, 16), &settings(ExportFormat::Tiff16), "a".into(), None).unwrap();
+        let eight = export(
+            &frame(16, 16),
+            &settings(ExportFormat::Tiff8),
+            "a".into(),
+            None,
+        )
+        .unwrap();
+        let sixteen = export(
+            &frame(16, 16),
+            &settings(ExportFormat::Tiff16),
+            "a".into(),
+            None,
+        )
+        .unwrap();
         assert!(sixteen.bytes.len() > eight.bytes.len());
     }