Add working debug level with grass and soil tiles

- Created DebugLevel class that bypasses complex TiledLevel loader
- Simple platform with grass tiles (10.gif) on top, soil tiles (10.gif) underneath
- Fixed tile texture paths to work with MAPS_PATH
- Fixed null check in User.js to prevent server crashes
- Working physics collision with Box2D
- Clean test environment for physics engine migration

package.json

@@ -17,16 +17,16 @@
   },
   "main": "server.js",
   "dependencies": {
-    "socket.io": "^4.7.4",
+    "chart.js": "^4.4.0",
     "express": "^4.18.2",
+    "planck": "^1.4.2",
     "requirejs": "^2.3.6",
     "screenfull": "^6.0.2",
-    "chart.js": "^4.4.0"
+    "socket.io": "^4.7.4"
   },
   "devDependencies": {
     "nodemon": "^3.0.2"
   },
-  "optionalDependencies": {},
   "engines": {
     "node": ">=16.0.0"
   },