Added minification of board images in stylesheets

package.json

@@ -14,10 +14,13 @@
     "@types/gif.js": "^0.2.2",
     "@types/hammerjs": "^2.0.41",
     "@types/howler": "^2.2.6",
+    "@types/imagemin": "^8.0.0",
     "@types/node": "^17.0.30",
     "@types/ua-parser-js": "^0.7.36",
     "@vitejs/plugin-legacy": "^1.8.1",
     "canvas": "^2.9.1",
+    "imagemin": "^7.0.1",
+    "imagemin-pngquant": "^9.0.2",
     "mime": "^3.0.0",
     "npm": "^8.8.0",
     "typescript": "^4.4.4",