updated applet seed migration to include default applet sizes; other sundry styling refinements

src/static_src/scss/_palette-picker.scss

@@ -7,6 +7,13 @@
     -webkit-overflow-scrolling: touch;
     gap: 0.75rem;
     padding-bottom: 0.5rem;
+    mask-image: linear-gradient(
+        to right,
+        transparent 0%,
+        black 8%,
+        black 92%,
+        transparent 100%
+    );
 }
 
 .palette-item {
@@ -14,13 +21,13 @@
     flex-direction: column;
     align-items: center;
     gap: 0.5rem;
-    flex: 0 0 calc(100% / 3);
+    flex: 0 0 calc(50% - 0.375rem);
     scroll-snap-align: start;
 }
 
 .swatch {
-    width: 4rem;
-    height: 4rem;
+    width: 100%;
+    aspect-ratio: 1;
     border-radius: 0.5rem;
     background: linear-gradient(
         to bottom,