Add premium configurator with split-screen layout

- Redesigned configurator page with split-screen interface
- Left: Large visual preview with sticky positioning
- Right: Premium white controls container with form steps
- Added complete configurator wizard (5 steps)
- Updated hero CTA to "Zelf ontwerpen"
- Configured Shadcn UI with Slate theme
- Added layout components (Navbar, Footer)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

components/ui/radio-group.tsx

@@ -0,0 +1,45 @@
+"use client"
+
+import * as React from "react"
+import { CircleIcon } from "lucide-react"
+import { RadioGroup as RadioGroupPrimitive } from "radix-ui"
+
+import { cn } from "@/lib/utils"
+
+function RadioGroup({
+  className,
+  ...props
+}: React.ComponentProps<typeof RadioGroupPrimitive.Root>) {
+  return (
+    <RadioGroupPrimitive.Root
+      data-slot="radio-group"
+      className={cn("grid gap-3", className)}
+      {...props}
+    />
+  )
+}
+
+function RadioGroupItem({
+  className,
+  ...props
+}: React.ComponentProps<typeof RadioGroupPrimitive.Item>) {
+  return (
+    <RadioGroupPrimitive.Item
+      data-slot="radio-group-item"
+      className={cn(
+        "border-input text-primary focus-visible:border-ring focus-visible:ring-ring/50 aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive dark:bg-input/30 aspect-square size-4 shrink-0 rounded-full border shadow-xs transition-[color,box-shadow] outline-none focus-visible:ring-[3px] disabled:cursor-not-allowed disabled:opacity-50",
+        className
+      )}
+      {...props}
+    >
+      <RadioGroupPrimitive.Indicator
+        data-slot="radio-group-indicator"
+        className="relative flex items-center justify-center"
+      >
+        <CircleIcon className="fill-primary absolute top-1/2 left-1/2 size-2 -translate-x-1/2 -translate-y-1/2" />
+      </RadioGroupPrimitive.Indicator>
+    </RadioGroupPrimitive.Item>
+  )
+}
+
+export { RadioGroup, RadioGroupItem }