Add cloth simulation page with WGSL shaders

Introduce a new cloth simulation feature: adds ClothComponent (TS/HTML/SCSS) and WGSL compute/vertex/fragment shaders implementing an XPBD-based cloth sim. Wire up routing and RouterConstants, add the cloth entry to the algorithms list, and add English/German i18n strings. Also include small refactors/renames for algorithm-category and algorithms.service imports and update BabylonCanvas to tolerate optional shader configuration and avoid null access during setup.

src/app/shared/rendering/canvas/babylon-canvas.component.ts

@@ -5,9 +5,9 @@ export interface RenderConfig {
   mode: '2D' | '3D';
   shaderLanguage?: number; //0 GLSL, 1 WGSL
   initialViewSize: number;
-  vertexShader: string;
-  fragmentShader: string;
-  uniformNames: string[];
+  vertexShader?: string;
+  fragmentShader?: string;
+  uniformNames?: string[];
   uniformBufferNames?: string[];
 }
 
@@ -120,8 +120,10 @@ export class BabylonCanvas implements AfterViewInit, OnDestroy {
   }
 
   private createFullScreenRect() {
+    if (!this.config.vertexShader || !this.config.fragmentShader) {
+      return;
+    }
     const plane = MeshBuilder.CreatePlane("plane", {size: 100}, this.scene);
-
     if (this.config.mode === '3D') {
       plane.parent = this.camera;
       plane.position.z = 1;
@@ -134,6 +136,10 @@ export class BabylonCanvas implements AfterViewInit, OnDestroy {
   }
 
   private createShaderMaterial() {
+    if (!this.config.vertexShader || !this.config.fragmentShader || !this.config.uniformNames) {
+      return;
+    }
+
     this.shaderMaterial = new ShaderMaterial(
       "shaderMaterial",
       this.scene,
@@ -161,8 +167,10 @@ export class BabylonCanvas implements AfterViewInit, OnDestroy {
       }
 
       // default uniforms which maybe each scene has
-      this.shaderMaterial.setVector2("resolution", new Vector2(canvas.width, canvas.height));
-      this.shaderMaterial.setVector3("cameraPosition", this.camera.position);
+      if (this.shaderMaterial) {
+        this.shaderMaterial.setVector2("resolution", new Vector2(canvas.width, canvas.height));
+        this.shaderMaterial.setVector3("cameraPosition", this.camera.position);
+      }
 
       this.scene.render();
     });