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-segment/examples/detect.rs

@@ -46,7 +46,11 @@ fn main() {
     };
     println!(
         "tiling     {}",
-        if tiled { "grid, 25% overlap" } else { "whole frame" }
+        if tiled {
+            "grid, 25% overlap"
+        } else {
+            "whole frame"
+        }
     );
 
     let t0 = std::time::Instant::now();
@@ -57,10 +61,7 @@ fn main() {
     let instances = model
         .detect(&rgb, width, height, &options)
         .expect("inference");
-    println!(
-        "detect     {:.0} ms",
-        t1.elapsed().as_secs_f32() * 1000.0
-    );
+    println!("detect     {:.0} ms", t1.elapsed().as_secs_f32() * 1000.0);
     println!("found      {} instances", instances.len());
 
     for (i, inst) in instances.iter().enumerate() {
@@ -131,10 +132,7 @@ fn load_jpeg(path: &str) -> (Vec<f32>, usize, usize) {
     // where *not* linearising is the correct thing to do.
     let rgb = match pixels.len() / (w * h) {
         3 => pixels.iter().map(|&v| v as f32 / 255.0).collect(),
-        1 => pixels
-            .iter()
-            .flat_map(|&v| [v as f32 / 255.0; 3])
-            .collect(),
+        1 => pixels.iter().flat_map(|&v| [v as f32 / 255.0; 3]).collect(),
         n => panic!("unexpected {n} components per pixel"),
     };