Replace the sample data with synthetic fixtures and regenerate goldens and thumbnails

The template harness, tests and thumbnails now use a neutral vendor, bank account and
a generated sample wordmark (scripts/logo/make-sample-logo.mjs). Layout goldens and the
14 picker thumbnails are regenerated. Fixture strings keep their original lengths where
layout tests depend on them.

src-tauri/src/logo.rs

@@ -540,8 +540,8 @@ mod tests {
         let out = process_logo(&bytes).unwrap();
         let m = &out.metrics;
         assert_eq!((m.source_width, m.source_height), (2172, 724));
-        assert!((4.5..=4.7).contains(&m.aspect), "aspect {}", m.aspect);
-        assert!((0.40..=0.46).contains(&m.ink_density), "density {}", m.ink_density);
+        assert!((5.3..=5.6).contains(&m.aspect), "aspect {}", m.aspect);
+        assert!((0.50..=0.60).contains(&m.ink_density), "density {}", m.ink_density);
         assert_eq!(m.kind, LogoKind::Wordmark);
         assert!(out.print_png.len() <= 120 * 1024, "print is {} bytes", out.print_png.len());
         assert!(out.knockout_png.is_some());