🎨(react) add UIKit theme support

Introduce new UIKit theme with light and dark variants, including
comprehensive color tokens for both themes. Update relevant components
and styles to accommodate the new theme architecture.

apps/demo/src/App.tsx

@@ -13,6 +13,7 @@ enum Theme {
   CUNNINGHAM = "cunningham",
   REDFLUX = "redflux",
   BLUENEY = "blueney",
+  UIKIT = "uikit"
 }
 
 enum Variant {
@@ -33,6 +34,10 @@ const THEMES: Record<Theme, Record<Variant, string | undefined>> = {
     light: undefined,
     dark: "blueney_dark",
   },
+  [Theme.UIKIT]: {
+    light: "uikit_light",
+    dark: "uikit_dark",
+  },
 };
 
 export type PageProps = ReturnType<typeof useModal>;