build: clean before building

Author: aminya

examples/quickstart/package-lock.json

@@ -13,7 +13,8 @@
     "LICENSE"
   ],
   "scripts": {
-    "build": "run-s lib:js:build",
+    "clean": "shx rm -rf dist",
+    "build": "run-s clean lib:js:build",
     "dev": "run-p lib:watch lib:test:watch",
     "serve": "serve dist -p 8080",
     "test": "run-s build test:lib test:quickstart",
@@ -82,6 +83,7 @@
     "rollup-plugin-terser": "^7.0.2",
     "sakura.css": "^1.0.0",
     "serve": "^11.2.0",
+    "shx": "^0.3.4",
     "tslib": "^2.3.1",
     "typescript": "^4.4.3"
   },