Keep the test scene's own arithmetic from overflowing a u64

The first compile this branch ever had. `cargo fmt` reflowed four files
and clippy passed at -D warnings untouched, but one test panicked:
`the_signature_does_not_change_with_scale`, on "attempt to multiply with
overflow".

It is the fixture, not the feature. `scene()`'s little LCG multiplied the
block's y by the golden-ratio constant with a plain `*` while the term
beside it already used `wrapping_mul`, so any scene taller than about 104
pixels overflowed in debug. Only the scale test builds one that large,
which is why 345 of 346 passed around it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ui/dr-ui/src/library.rs

@@ -5066,11 +5066,7 @@ mod tests {
                     "UPDATE images SET captured_at = ?2, camera = 'Canon EOS R5',
                                        perceptual_hash = ?3
                       WHERE id = ?1",
-                    rusqlite::params![
-                        id.0 as i64,
-                        1_000 + n as i64,
-                        Signature(hash).to_stored()
-                    ],
+                    rusqlite::params![id.0 as i64, 1_000 + n as i64, Signature(hash).to_stored()],
                 )
                 .unwrap();
         }