style: refine background pattern options

client/src/assets/main.css

@@ -97,6 +97,13 @@
   filter: contrast(160%) brightness(110%);
 }
 
+.pattern-polar-aurora {
+  background-image:
+    radial-gradient(120% 58% at 0% 22%, oklch(0.76 0.14 calc(var(--tint-h) + 20) / 0.13), transparent 68%),
+    radial-gradient(120% 58% at 100% 34%, oklch(0.74 0.14 calc(var(--tint-h) + 190) / 0.12), transparent 68%),
+    radial-gradient(130% 62% at 50% -12%, color-mix(in oklch, var(--primary) 14%, transparent), transparent 72%);
+}
+
 .pattern-isogrid::before {
   content: '';
   position: fixed;

client/src/stores/theme.ts

@@ -49,6 +49,7 @@ export type Background =
   | 'brushed'
   | 'prism'
   | 'spectrum'
+  | 'polar-aurora'
   | 'elevation'
   | 'terminal'
 
@@ -118,6 +119,7 @@ export const BACKGROUND_OPTIONS: { id: Background; label: string; cssClass: stri
   { id: 'elevation', label: 'Elevation', cssClass: 'pattern-elevation' },
   { id: 'prism', label: 'Prism', cssClass: 'pattern-prism' },
   { id: 'spectrum', label: 'Spectrum', cssClass: 'pattern-spectrum' },
+  { id: 'polar-aurora', label: 'Polar Aurora', cssClass: 'pattern-polar-aurora' },
 ]
 
 const ACCENT_IDS = ACCENT_OPTIONS.map((a) => a.id)