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-gpu/tests/local_adjustments.rs

@@ -65,12 +65,7 @@ fn render_at(
     h: u32,
 ) -> Vec<u8> {
     let source = grey_at(ctx, w, h);
-    let shader = compose_full(
-        &ops::chain(),
-        &Framing::new(),
-        ColourSpace::Srgb,
-        stack,
-    );
+    let shader = compose_full(&ops::chain(), &Framing::new(), ColourSpace::Srgb, stack);
 
     let mut masks = MaskPass::new(ctx).expect("mask pass");
     let array = masks.render(stack, field, None, w, h).expect("rasterise");
@@ -245,11 +240,14 @@ fn stacked_layers_use_their_own_masks() {
         ids: vec![0],
     }));
     // Right half down.
-    let mut darken = MaskLayer::new("m2", MaskSource::Regions {
-        signature: 1,
-        level: 2,
-        ids: vec![1],
-    });
+    let mut darken = MaskLayer::new(
+        "m2",
+        MaskSource::Regions {
+            signature: 1,
+            level: 2,
+            ids: vec![1],
+        },
+    );
     darken.set_param("exposure", ParamId("exposure"), -2.0);
     stack.push(darken);
 
@@ -412,12 +410,7 @@ fn a_stroke_that_doubles_back_does_not_build_up() {
         return;
     };
 
-    let once = stack_of(painted(&[(
-        false,
-        0.15,
-        0.5,
-        vec![(0.1, 0.5), (0.9, 0.5)],
-    )]));
+    let once = stack_of(painted(&[(false, 0.15, 0.5, vec![(0.1, 0.5), (0.9, 0.5)])]));
     let twice = stack_of(painted(&[(
         false,
         0.15,
@@ -473,10 +466,17 @@ fn a_dab_is_round_on_a_frame_that_is_not_square() {
     let pixels = render_at(&ctx, &stack, None, W, H);
 
     let lit = |v: u8| v > 160;
-    let across = (0..W).filter(|&x| lit(luma_in(&pixels, W, x, H / 2))).count();
-    let down = (0..H).filter(|&y| lit(luma_in(&pixels, W, W / 2, y))).count();
+    let across = (0..W)
+        .filter(|&x| lit(luma_in(&pixels, W, x, H / 2)))
+        .count();
+    let down = (0..H)
+        .filter(|&y| lit(luma_in(&pixels, W, W / 2, y)))
+        .count();
 
-    assert!(across > 4 && down > 4, "the dab should exist: {across}x{down}");
+    assert!(
+        across > 4 && down > 4,
+        "the dab should exist: {across}x{down}"
+    );
     assert!(
         across.abs_diff(down) <= 2,
         "a dab must be as wide as it is tall, got {across} across and {down} down"