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/assets/i18n/en.json

@@ -470,6 +470,9 @@
       "DISCLAIMER_BOTTOM": "NOTE: If too many impulses are fed into the system, the simulation becomes unstable. The pendulum will then just hang down and the simulation will have to be restarted."
     }
   },
+  "CLOTH": {
+    "TITLE": "Cloth simulation"
+  },
   "ALGORITHM": {
     "TITLE": "Algorithms",
     "PATHFINDING": {
@@ -500,6 +503,10 @@
       "TITLE": "Double pendulum",
       "DESCRIPTION": "Visualisation of a chaotic double pendulum simulation with WebGPU."
     },
+    "CLOTH": {
+      "TITLE": "Cloth simulation",
+      "DESCRIPTION": "Simulation of cloth with WebGPU."
+    },
     "NOTE": "Note",
     "GRID_HEIGHT": "Height",
     "GRID_WIDTH": "Width"