Format the refine tests the way the gate asks for it

`cargo fmt --check` is a required step and the mask-refine work landed with a
test body it disagrees with. Whitespace only — kept as its own commit so it can
be skipped wholesale rather than read for a change that matters.

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

ui/dr-ui/src/develop.rs

@@ -3046,8 +3046,9 @@ mod tests {
     fn a_slider_moved_with_two_layers_selected_moves_both() {
         let Some(ctx) = headless() else { return };
         let rgba: Vec<u8> = (0..8 * 8).flat_map(|_| [128u8, 128, 128, 255]).collect();
-        let mut session = DevelopSession::open_rgb(&ctx, &rgba, 8, 8, dr_types::Orientation::NORMAL)
-            .expect("session");
+        let mut session =
+            DevelopSession::open_rgb(&ctx, &rgba, 8, 8, dr_types::Orientation::NORMAL)
+                .expect("session");
 
         let a = session.add_gradient_mask(true).expect("first gradient");
         let b = session.add_gradient_mask(false).expect("second gradient");
@@ -3101,7 +3102,10 @@ mod tests {
         // Two rows, black then white: the exact midpoint reads as grey.
         let mask = [0.0f32, 0.0, 1.0, 1.0];
         let v = bilinear_sample(&mask, 2, 2, 0.5, 0.5);
-        assert!((v - 0.5).abs() < 1e-6, "expected the midpoint grey, got {v}");
+        assert!(
+            (v - 0.5).abs() < 1e-6,
+            "expected the midpoint grey, got {v}"
+        );
     }
 
     /// A control-click twice — once to add, once to remove — is a no-op on
@@ -3111,8 +3115,9 @@ mod tests {
     fn toggling_a_layer_twice_returns_to_the_starting_selection() {
         let Some(ctx) = headless() else { return };
         let rgba: Vec<u8> = (0..8 * 8).flat_map(|_| [128u8, 128, 128, 255]).collect();
-        let mut session = DevelopSession::open_rgb(&ctx, &rgba, 8, 8, dr_types::Orientation::NORMAL)
-            .expect("session");
+        let mut session =
+            DevelopSession::open_rgb(&ctx, &rgba, 8, 8, dr_types::Orientation::NORMAL)
+                .expect("session");
 
         let a = session.add_gradient_mask(true).expect("gradient");
         assert_eq!(session.active_masks(), [a.clone()].as_slice());