feat: Add professional 3D handles, glass patterns, and living room scene

✨ New Features:
- 6 procedural 3D handles (Beugelgreep, Hoekgreep, Maangreep, Ovaalgreep, Klink, U-greep)
- Glass pattern generator (Standard, DT9 rounded corners, DT10 U-shapes)
- Dynamic living room scene with adaptive doorway
- Enhanced camera controls (zoomed out, more freedom)
- Texture loading system (prepared for future enhancement)

🎨 Visual Improvements:
- Professional handle details (screws, mounting blocks, rosettes)
- Realistic materials (metalness 0.95, proper roughness)
- Living room context (wood floor, white walls, baseboards)
- Better lighting (sunlight simulation, fill lights)
- Apartment environment preset

🏗️ Technical:
- Parametric glass shapes with THREE.Shape
- Dynamic doorway sizing based on door dimensions
- Store updates for handle and glass pattern types
- UI components for all new options

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

components/configurator/texture-loader.tsx

@@ -0,0 +1,80 @@
+"use client";
+
+import { useTexture } from "@react-three/drei";
+import { useEffect, useState } from "react";
+import * as THREE from "three";
+
+/**
+ * Preload textures to prevent loading freezes
+ * Uses Suspense boundary for progressive loading
+ */
+export function useMetalTexture(finish: string) {
+  const [textureUrl, setTextureUrl] = useState<string | null>(null);
+
+  useEffect(() => {
+    const mapping: Record<string, string> = {
+      zwart: "/textures/aluwdoors/aluwdoors-configurator-metaalkleur-zwart.jpg",
+      brons: "/textures/aluwdoors/aluwdoors-configurator-metaalkleur-brons.jpg",
+      grijs: "/textures/aluwdoors/aluwdoors-configurator-metaalkleur-antraciet.jpg",
+    };
+
+    setTextureUrl(mapping[finish] || mapping.zwart);
+  }, [finish]);
+
+  try {
+    if (!textureUrl) return null;
+
+    // Load texture with useTexture
+    const texture = useTexture(textureUrl);
+
+    // Configure texture for optimal rendering
+    if (texture) {
+      texture.wrapS = texture.wrapT = THREE.RepeatWrapping;
+      texture.repeat.set(2, 2);
+      texture.colorSpace = THREE.SRGBColorSpace;
+    }
+
+    return texture;
+  } catch (error) {
+    // Fallback: return null if texture fails to load
+    console.warn("Texture loading failed, using solid color fallback", error);
+    return null;
+  }
+}
+
+/**
+ * Enhanced Steel Material with texture support
+ */
+export function SteelMaterialWithTexture({
+  color,
+  finish,
+}: {
+  color: string;
+  finish: string;
+}) {
+  const texture = useMetalTexture(finish);
+
+  return (
+    <meshStandardMaterial
+      map={texture}
+      color={color}
+      roughness={0.7}
+      metalness={0.8}
+      envMapIntensity={1.2}
+    />
+  );
+}
+
+/**
+ * Fallback Steel Material (solid color)
+ */
+export function SteelMaterialSolid({ color }: { color: string }) {
+  return (
+    <meshStandardMaterial
+      color={color}
+      roughness={0.7}
+      metalness={0.8}
+      envMapIntensity={1}
+    />
+  );
+}