feat: persist browser sessions and update admin workflows

backend/app/utils/dingtalk.py

@@ -64,6 +64,25 @@ def format_dingtalk_website_rate_changed(
     }
 
 
+def format_dingtalk_balance_low(
+    upstream_name: str, balance: float, threshold: float, changed_at: str
+) -> dict[str, Any]:
+    lines = [
+        f"### ⚠️ {upstream_name} 余额不足",
+        "",
+        f"- **当前余额**：{balance:.2f}",
+        f"- **告警阈值**：{threshold:.2f}",
+        f"- **时间**：{changed_at}",
+    ]
+    return {
+        "msgtype": "markdown",
+        "markdown": {
+            "title": f"{upstream_name} 余额不足",
+            "text": "\n".join(lines),
+        },
+    }
+
+
 def format_dingtalk_status(upstream_name: str, event: str, changed_at: str, error: str = "") -> dict[str, Any]:
     emoji = "🔴" if event == "upstream_unhealthy" else "🟢"
     label = "服务异常" if event == "upstream_unhealthy" else "服务恢复"