style(bench): rustfmt ewa_syrk_crossover + canonical -C target-cpu in RESULTS

Fixes CI cargo fmt --all --check (rustfmt 1.95.0: wrap the use import,
normalize_quat method chain, and Spd3::new args) and the CodeRabbit nit on
RESULTS.md (canonical `-C target-cpu` spelling with a space). Docs/format
only; no behavior change.

https://claude.ai/code/session_01HbqooFZHAjaUtFEzhA1R2u

Author: claude

benches/RESULTS.md

@@ -139,7 +139,7 @@ project's deployment tier `x86-64-v4`** (AVX-512 native — `F32x16` is a
 single `__m512`), via the documented override:
 
 ```bash
-RUSTFLAGS="-Ctarget-cpu=x86-64-v4" \
+RUSTFLAGS="-C target-cpu=x86-64-v4" \
   cargo bench --features splat3d --bench ewa_syrk_crossover
 ```
 

benches/ewa_syrk_crossover.rs

@@ -38,7 +38,9 @@
 //! gaussian, so `J·Σ·Jᵀ` does not batch that way.
 
 use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
-use ndarray::hpc::splat3d::{project_batch, sandwich, sandwich_x16, Camera, Gaussian3D, GaussianBatch, ProjectedBatch, Spd3};
+use ndarray::hpc::splat3d::{
+    project_batch, sandwich, sandwich_x16, Camera, Gaussian3D, GaussianBatch, ProjectedBatch, Spd3,
+};
 
 const SIZES: [usize; 3] = [1_024, 100_000, 1_000_000];
 
@@ -70,7 +72,9 @@ fn build_spd_pairs(n: usize) -> (Vec<Spd3>, Vec<Spd3>) {
 }
 
 fn normalize_quat(q: &mut [f32; 4]) {
-    let n = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]).sqrt().max(1e-12);
+    let n = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3])
+        .sqrt()
+        .max(1e-12);
     for v in q.iter_mut() {
         *v /= n;
     }
@@ -96,7 +100,14 @@ fn sandwich_gemm_shape(m: &Spd3, n: &Spd3) -> Spd3 {
             r[i][j] = t[i][0] * a[j][0] + t[i][1] * a[j][1] + t[i][2] * a[j][2];
         }
     }
-    Spd3::new(r[0][0], 0.5 * (r[0][1] + r[1][0]), 0.5 * (r[0][2] + r[2][0]), r[1][1], 0.5 * (r[1][2] + r[2][1]), r[2][2])
+    Spd3::new(
+        r[0][0],
+        0.5 * (r[0][1] + r[1][0]),
+        0.5 * (r[0][2] + r[2][0]),
+        r[1][1],
+        0.5 * (r[1][2] + r[2][1]),
+        r[2][2],
+    )
 }
 
 fn build_gaussians(n: usize) -> GaussianBatch {