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

demo/data/polar.js

@@ -0,0 +1,52 @@
+const data = [];
+
+for (let i = 0; i <= 360; i++) {
+  const t = (i / 180) * Math.PI;
+  const r = Math.sin(2 * t) * Math.cos(2 * t);
+  data.push([r, i]);
+}
+
+export default function getData() {
+  return {
+    textStyle: {
+      fontFamily: 'Inter, "Helvetica Neue", Arial, sans-serif',
+      fontWeight: 300
+    },
+    title: {
+      text: "Dual Numeric Axis",
+      top: "5%",
+      left: "5%"
+    },
+    legend: {
+      data: ["line"],
+      top: "6%"
+    },
+    polar: {
+      radius: "65%",
+      center: ["50%", "56%"]
+    },
+    tooltip: {
+      trigger: "axis",
+      axisPointer: {
+        type: "cross"
+      }
+    },
+    angleAxis: {
+      type: "value",
+      startAngle: 0
+    },
+    radiusAxis: {
+      min: 0
+    },
+    series: [
+      {
+        coordinateSystem: "polar",
+        name: "line",
+        type: "line",
+        showSymbol: false,
+        data: data
+      }
+    ],
+    animationDuration: 2000
+  };
+}