feat: support radar option of echarts

examples/charts/main.go

@@ -1483,6 +1483,75 @@ func echartsHandler(w http.ResponseWriter, req *http.Request) {
 				}
 			]
 		}`,
+		`{
+			"title": {
+				"text": "Basic Radar Chart"
+			},
+			"legend": {
+				"data": [
+					"Allocated Budget",
+					"Actual Spending"
+				]
+			},
+			"radar": {
+				"indicator": [
+					{
+						"name": "Sales",
+						"max": 6500
+					},
+					{
+						"name": "Administration",
+						"max": 16000
+					},
+					{
+						"name": "Information Technology",
+						"max": 30000
+					},
+					{
+						"name": "Customer Support",
+						"max": 38000
+					},
+					{
+						"name": "Development",
+						"max": 52000
+					},
+					{
+						"name": "Marketing",
+						"max": 25000
+					}
+				]
+			},
+			"series": [
+				{
+					"name": "Budget vs spending",
+					"type": "radar",
+					"data": [
+						{
+							"value": [
+								4200,
+								3000,
+								20000,
+								35000,
+								50000,
+								18000
+							],
+							"name": "Allocated Budget"
+						},
+						{
+							"value": [
+								5000,
+								14000,
+								28000,
+								26000,
+								42000,
+								21000
+							],
+							"name": "Actual Spending"
+						}
+					]
+				}
+			]
+		}`,
 		`{
 			"legend": {
 				"top": "-140",