build: migrate demo from webpack to Vite (#832)

demo/data/pie.js

@@ -0,0 +1,45 @@
+export default function getData() {
+  return {
+    textStyle: {
+      fontFamily: 'Inter, "Helvetica Neue", Arial, sans-serif',
+      fontWeight: 300
+    },
+    title: {
+      text: "Traffic Sources",
+      top: "5%",
+      left: "center"
+    },
+    tooltip: {
+      trigger: "item",
+      formatter: "{a} <br/>{b} : {c} ({d}%)"
+    },
+    legend: {
+      orient: "vertical",
+      top: "5%",
+      left: "5%",
+      data: ["Direct", "Email", "Ad Networks", "Video Ads", "Search Engines"]
+    },
+    series: [
+      {
+        name: "Traffic Sources",
+        type: "pie",
+        radius: "55%",
+        center: ["50%", "60%"],
+        data: [
+          { value: 335, name: "Direct" },
+          { value: 310, name: "Email" },
+          { value: 234, name: "Ad Networks" },
+          { value: 135, name: "Video Ads" },
+          { value: 1548, name: "Search Engines" }
+        ],
+        emphasis: {
+          itemStyle: {
+            shadowBlur: 10,
+            shadowOffsetX: 0,
+            shadowColor: "rgba(0, 0, 0, 0.5)"
+          }
+        }
+      }
+    ]
+  };
+}