Add CLAUDE.md, use snackbar for WebGPU errors

Add a new CLAUDE.md project guidelines file. Update BabylonCanvas to replace alert() with an Angular Material MatSnackBar and use ngx-translate for a localized WebGPU-not-supported message (injects MatSnackBar and TranslateService and updates imports). Add the corresponding WEBGPU.NOT_SUPPORTED entries to en.json and de.json for localization.

src/assets/i18n/en.json

@@ -499,6 +499,9 @@
       "DISCLAIMER_4": "The XPBD Compromise: XPBD completely bypasses this complex matrix problem by acting as a local solver. It combines the absolute stability of an implicit solver with the enormous speed, parallelizability, and dynamic adaptability of an explicit system."
     }
   },
+  "WEBGPU": {
+    "NOT_SUPPORTED": "WebGPU could not be started. Please check if your browser supports WebGPU."
+  },
   "ALGORITHM": {
     "TITLE": "Algorithms",
     "PATHFINDING": {