feat: revamp demo

demo/utils/geo.ts

@@ -0,0 +1,16 @@
+import type { registerMap } from "echarts/core";
+
+type GeoJSONInput = Parameters<typeof registerMap>[1];
+
+type FeatureCollectionLike = { type?: unknown };
+
+export function isGeoJSONSource(value: unknown): value is GeoJSONInput {
+  if (typeof value === "string") {
+    return true;
+  }
+  if (value && typeof value === "object" && "type" in value) {
+    const type = (value as FeatureCollectionLike).type;
+    return type === "FeatureCollection";
+  }
+  return false;
+}