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>

core/dr-face/src/calibrate.rs

@@ -108,10 +108,7 @@ impl Calibration {
     /// What turns "merge above 0.9" into one comparison against a stored
     /// similarity, rather than a sigmoid evaluated per candidate edge.
     pub fn boundary_at(&self, p: f32, min_crop_px: f32, log_prior_odds: f32) -> f32 {
-        ((p / (1.0 - p)).ln()
-            - self.b
-            - self.w_size * min_crop_px.max(1.0).log2()
-            - log_prior_odds)
+        ((p / (1.0 - p)).ln() - self.b - self.w_size * min_crop_px.max(1.0).log2() - log_prior_odds)
             / self.a
     }
 }
@@ -416,7 +413,10 @@ mod tests {
                 b.count
             );
         }
-        assert!(checked >= 2, "only {checked} bands had enough pairs to check");
+        assert!(
+            checked >= 2,
+            "only {checked} bands had enough pairs to check"
+        );
     }
 
     #[test]