feat: migrate to Radix UI and implement dark mode with next-themes

Replace @headlessui/react and @heroicons/react with @radix-ui/themes and
@radix-ui/react-icons for a more comprehensive component library. Add
next-themes for dark mode support with a new ThemeToggle component. Update
all components to use Radix UI primitives and theming system, including
AbstractCard, DynamicDate, ErrorCard, Property, PropertyList, LookupInput,
and all card components (AutnumCard, DomainCard, EntityCard, IPCard,
NameserverCard). Update global styles and app configuration to support theme
switching.

package.json

@@ -22,12 +22,13 @@
 	"dependencies": {
 		"@fontsource-variable/inter": "^5.2.8",
 		"@fontsource/ibm-plex-mono": "^5.2.7",
-		"@headlessui/react": "^2.2.9",
-		"@heroicons/react": "^2.0.16",
+		"@radix-ui/react-icons": "^1.3.2",
+		"@radix-ui/themes": "^3.2.1",
 		"@swc/helpers": "^0.5.11",
 		"clsx": "^2.1.1",
 		"date-fns": "^4.1.0",
 		"next": "^15.5.6",
+		"next-themes": "^0.4.6",
 		"react": "19.2.0",
 		"react-dom": "19.2.0",
 		"react-hook-form": "^7.42.1",