feat: black theme and other UI fixes

src/theme/index.ts

@@ -1,12 +1,14 @@
 export {
   MD3LightColors,
   MD3DarkColors,
+  MD3BlackColors,
   MD3Typography,
   MD3Elevation,
   MD3Shape,
   Spacing,
   LightTheme,
   DarkTheme,
+  BlackTheme,
 } from './md3';
 export type {MD3Theme, MD3ColorScheme} from './md3';
 export {ThemeProvider, useTheme} from './ThemeProvider';