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-pipeline/tests/tone_curve.rs

@@ -12,7 +12,8 @@ use dr_pipeline::{EditGraph, Sidecar};
 
 /// A version block carrying `params`, in the on-disk spelling.
 fn sidecar_with(params: &[(&str, f32)]) -> String {
-    let mut text = String::from("drsc 1\n\n[version u1]\nname = Default\nrevision = 2\nmodified = 0\n");
+    let mut text =
+        String::from("drsc 1\n\n[version u1]\nname = Default\nrevision = 2\nmodified = 0\n");
     for (key, value) in params {
         text.push_str(&format!("{key} = {value}\n"));
     }
@@ -199,4 +200,3 @@ fn every_point_of_every_curve_round_trips_through_a_sidecar() {
         }
     }
 }
-