ADD: 修改数据合并逻辑，新增 event-source-polyfill包，实现长连接通信，展示合并进度

frontend/package.json

@@ -14,6 +14,7 @@
   },
   "dependencies": {
     "@element-plus/icons-vue": "^2.3.1",
+    "@types/event-source-polyfill": "^1.0.5",
     "@vue-flow/core": "^1.45.0",
     "@vueuse/core": "^10.4.1",
     "axios": "^1.7.3",
@@ -23,6 +24,7 @@
     "echarts": "^5.4.3",
     "echarts-liquidfill": "^3.1.0",
     "element-plus": "^2.7.8",
+    "event-source-polyfill": "^1.0.31",
     "html2canvas": "^1.4.1",
     "md5": "^2.3.0",
     "mitt": "^3.0.1",