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/examples/local.rs

@@ -26,9 +26,7 @@
 //! mask pinned to the viewport, a slice read from the wrong layer — shows up
 //! here as an adjustment in the wrong place, and nowhere else.
 
-use dr_gpu::{
-    AdjustPass, DemosaicedImage, Demosaicer, GpuContext, MaskPass, SubjectMasks,
-};
+use dr_gpu::{AdjustPass, DemosaicedImage, Demosaicer, GpuContext, MaskPass, SubjectMasks};
 use dr_pipeline::descriptor::ParamId;
 use dr_pipeline::mask::{MaskLayer, MaskSource, MaskStack, Morphology};
 use dr_pipeline::operation::compose_full;
@@ -152,7 +150,18 @@ fn main() {
     drain.feather = 0.02;
     pop.push(drain);
 
-    render_stack(&ctx, &source, &mut masks, &mut adjust, &pop, &alpha, pw, ph, ow, oh);
+    render_stack(
+        &ctx,
+        &source,
+        &mut masks,
+        &mut adjust,
+        &pop,
+        &alpha,
+        pw,
+        ph,
+        ow,
+        oh,
+    );
     write(&format!("{prefix}-colour-pop.ppm"), &adjust);
 
     // ---- 2. lift the subject out of its background ------------------------
@@ -170,7 +179,18 @@ fn main() {
     darker.feather = 0.03;
     lift.push(darker);
 
-    render_stack(&ctx, &source, &mut masks, &mut adjust, &lift, &alpha, pw, ph, ow, oh);
+    render_stack(
+        &ctx,
+        &source,
+        &mut masks,
+        &mut adjust,
+        &lift,
+        &alpha,
+        pw,
+        ph,
+        ow,
+        oh,
+    );
     write(&format!("{prefix}-subject-lift.ppm"), &adjust);
 
     // ---- 3. the same edit, grown and shrunk -------------------------------
@@ -192,7 +212,18 @@ fn main() {
         layer.morph_radius = radius;
         stack.push(layer);
 
-        render_stack(&ctx, &source, &mut masks, &mut adjust, &stack, &alpha, pw, ph, ow, oh);
+        render_stack(
+            &ctx,
+            &source,
+            &mut masks,
+            &mut adjust,
+            &stack,
+            &alpha,
+            pw,
+            ph,
+            ow,
+            oh,
+        );
         write(&format!("{prefix}-{name}.ppm"), &adjust);
     }
 
@@ -292,12 +323,18 @@ fn render_stack(
 
 fn fit(w: u32, h: u32, longest: u32) -> (u32, u32) {
     let s = (longest as f32 / w.max(h) as f32).min(1.0);
-    (((w as f32 * s) as u32).max(1), ((h as f32 * s) as u32).max(1))
+    (
+        ((w as f32 * s) as u32).max(1),
+        ((h as f32 * s) as u32).max(1),
+    )
 }
 
 fn write(path: &str, adjust: &AdjustPass) {
     let (rgba, w, h) = adjust.export_pixels().expect("readback");
-    let rgb: Vec<u8> = rgba.chunks_exact(4).flat_map(|p| [p[0], p[1], p[2]]).collect();
+    let rgb: Vec<u8> = rgba
+        .chunks_exact(4)
+        .flat_map(|p| [p[0], p[1], p[2]])
+        .collect();
     write_ppm(path, &rgb, w, h);
 }
 

core/dr-gpu/examples/segment.rs

@@ -12,8 +12,8 @@
 //! PPM for the same reason `develop` uses it: no encoder dependency, and
 //! every viewer reads it. This is a diagnostic, not an export path.
 
-use dr_segment::{MergeTree, RegionField};
 use dr_gpu::{DemosaicedImage, Demosaicer, GpuContext, SegmentOptions, SegmentPass};
+use dr_segment::{MergeTree, RegionField};
 
 /// The ladder the example dumps. Chosen to span "far too fine to be useful"
 /// through "one or two objects", because both ends are informative: if no rung