Run the formatter over the face branch before it reaches CI

The merge of the SCRFD/MobileFaceNet work brought 69 rustfmt diffs across
dr-catalog, dr-face and dr-ui with it, so `cargo fmt --all -- --check` fails
on master and the Desktop job stops at its Format step — before clippy, the
tests or the release build have run at all. That makes the whole desktop
half of CI blind: a real compile error behind this would look exactly the
same from the outside. There was nothing behind it, as it turns out — with
the formatting fixed, clippy, the test suite and the release build all pass.

Every .rs hunk is `cargo fmt --all` on the pinned 1.92.0 toolchain, not a
hand edit, but it is worth being precise about what that moved, because it
is more than whitespace. Besides reflowing signatures and call chains,
rustfmt reordered the `pub mod` and `pub use` items in dr-face/src/lib.rs so
the `#[cfg(feature = "inference")]` entries sort in place, added the trailing
semicolon inside `let ... else { return }` bodies in identity_ui.rs, wrapped
a bare closure body in braces in cluster.rs, adjusted trailing commas, and
dropped a stray blank line at the end of identity_ui.rs. All of it is
semantically inert; none of it changes behaviour.

docs/traceability.md rides along because it has to. The matrix records each
TRACES tag by line number, and reflowing develop.rs, lib.rs, faces.rs,
identity.rs and identity_ui.rs moved them — FR-CAT-8, FR-CAT-9, FR-CULL-10,
FR-DEV-3, FR-DEV-3a and FR-DEV-3c all shift by a line or two. The matrix was
verified up to date on d777f7f before this commit, so this is drift these
formatting changes introduced, not pre-existing staleness being swept up.
Leaving it for a follow-up commit would hand traceability-check.yml a
failure caused entirely by a whitespace change.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ui/dr-ui/src/faces.rs

@@ -314,15 +314,15 @@ pub fn spawn_face_sweep(
                 return;
             }
         };
-        let mut embedder = match Embedder::from_path(&embedder_model, ModelId::new(model_id.clone()))
-        {
-            Ok(e) => e,
-            Err(e) => {
-                log::warn!("face sweep: cannot load the embedder: {e}");
-                finish_empty(&tx);
-                return;
-            }
-        };
+        let mut embedder =
+            match Embedder::from_path(&embedder_model, ModelId::new(model_id.clone())) {
+                Ok(e) => e,
+                Err(e) => {
+                    log::warn!("face sweep: cannot load the embedder: {e}");
+                    finish_empty(&tx);
+                    return;
+                }
+            };
 
         let wanted = match faces_outstanding(&catalog, &store, &model_id) {
             Ok(w) => w,
@@ -723,7 +723,13 @@ mod tests {
 
     #[test]
     fn landmarks_normalise_against_the_long_edge() {
-        let lm = [(512.0, 256.0), (0.0, 0.0), (1024.0, 512.0), (10.0, 20.0), (5.0, 5.0)];
+        let lm = [
+            (512.0, 256.0),
+            (0.0, 0.0),
+            (1024.0, 512.0),
+            (10.0, 20.0),
+            (5.0, 5.0),
+        ];
         let n = normalise_landmarks(&lm, 1024.0);
         assert!((n[0].0 - 0.5).abs() < 1e-6);
         assert!((n[0].1 - 0.25).abs() < 1e-6);