fix: 保留用户/规则高级设置并增强节点运行时恢复 (#468)

* fix: 用户编辑时 maxConn 字段未正确回填

- User 接口添加 maxConn 类型定义
- handleEdit 中回填 maxConn 值
- normalizeUserItem 添加 maxConn 字段处理

解决编辑用户时最大连接数显示为 0 的问题

* fix: 保留转发设置并增强节点运行时恢复

go-backend/internal/http/handler/forward_proxy_protocol_test.go

@@ -0,0 +1,98 @@
+package handler
+
+import (
+	"testing"
+	"time"
+
+	"go-backend/internal/store/model"
+	"go-backend/internal/store/repo"
+)
+
+func TestBuildForwardServiceConfigsPreservesProxyProtocolWithInterfaceMetadata(t *testing.T) {
+	forward := &forwardRecord{
+		ID:            1,
+		UserID:        2,
+		TunnelID:      3,
+		RemoteAddr:    "1.1.1.1:443",
+		Strategy:      "fifo",
+		ProxyProtocol: 2,
+	}
+	tunnel := &tunnelRecord{Type: 1}
+	node := &nodeRecord{
+		InterfaceName: "eth0",
+		TCPListenAddr: "0.0.0.0",
+		UDPListenAddr: "0.0.0.0",
+	}
+
+	services := buildForwardServiceConfigs("1_2_3", forward, tunnel, node, 4001, "", nil, "")
+	if len(services) != 2 {
+		t.Fatalf("expected 2 services, got %d", len(services))
+	}
+
+	for _, service := range services {
+		metadata, ok := service["metadata"].(map[string]interface{})
+		if !ok {
+			t.Fatalf("expected metadata map, got %T", service["metadata"])
+		}
+		if metadata["interface"] != "eth0" {
+			t.Fatalf("expected interface metadata eth0, got %v", metadata["interface"])
+		}
+		if metadata["proxyProtocol"] != 2 {
+			t.Fatalf("expected proxyProtocol 2, got %v", metadata["proxyProtocol"])
+		}
+	}
+}
+
+func TestRollbackForwardMutationRestoresProxyProtocol(t *testing.T) {
+	r, err := repo.Open(":memory:")
+	if err != nil {
+		t.Fatalf("open repo: %v", err)
+	}
+	defer r.Close()
+
+	now := time.Now().UnixMilli()
+	if err := r.DB().Create(&model.Forward{
+		UserID:        2,
+		UserName:      "rollback-user",
+		Name:          "rollback-forward",
+		TunnelID:      3,
+		RemoteAddr:    "9.9.9.9:443",
+		Strategy:      "fifo",
+		CreatedTime:   now,
+		UpdatedTime:   now,
+		Status:        1,
+		ProxyProtocol: 2,
+	}).Error; err != nil {
+		t.Fatalf("create forward: %v", err)
+	}
+
+	forwardID := mustLastInsertID(t, r, "rollback-forward")
+	if err := r.DB().Model(&model.Forward{}).Where("id = ?", forwardID).Updates(map[string]interface{}{
+		"name":           "changed-forward",
+		"proxy_protocol": 0,
+		"updated_time":   now + 1,
+	}).Error; err != nil {
+		t.Fatalf("mutate forward: %v", err)
+	}
+
+	h := &Handler{repo: r}
+	h.rollbackForwardMutation(&forwardRecord{
+		ID:            forwardID,
+		UserID:        2,
+		UserName:      "rollback-user",
+		Name:          "rollback-forward",
+		TunnelID:      3,
+		RemoteAddr:    "9.9.9.9:443",
+		Strategy:      "fifo",
+		Status:        1,
+		ProxyProtocol: 2,
+	}, nil)
+
+	var proxyProtocol int
+	if err := r.DB().Raw("SELECT proxy_protocol FROM forward WHERE id = ?", forwardID).Row().Scan(&proxyProtocol); err != nil {
+		t.Fatalf("query proxy_protocol: %v", err)
+	}
+	if proxyProtocol != 2 {
+		t.Fatalf("expected proxyProtocol restored to 2, got %d", proxyProtocol)
+	}
+}