feat(server): 私有服务域名分流(PANGOLIN_PRIVATE_SPLIT_DOMAINS)

家庭内网穿透域名(nas/git/win.yanmeiai.com)的客户端配置渲染:
- DNS 面: 系统解析器(type=local,底层网络)+私有域名规则置顶+reverse_mapping
- 路由面: 私有域名→强制走隧道,钉在 LAN 直连之后、国内分流(geoip-cn)之前
在家: 局域网 DNS 覆盖→私网IP→LAN直连零绕行; 在外: 锚点(frps@ali,国内IP)
不再被 smartRoute 分流成直连、避开安全组限源。env 不配置=行为零变化。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/internal/httpapi/nodes.go

@@ -42,12 +42,16 @@ type NodeAPI struct {
 	// rulesBaseURL 是控制面对外公网基址(PANGOLIN_PUBLIC_URL),供国内分流的
 	// rule_set .srs 下载用;空则分流不生效。
 	rulesBaseURL string
+	// privateSplitDomains 私有服务域名(PANGOLIN_PRIVATE_SPLIT_DOMAINS,逗号分隔),
+	// 见 ClientConfigOpts.PrivateSplitDomains;空则不渲染相关规则。
+	privateSplitDomains []string
 }
 
 // NewNodeAPI creates a NodeAPI. load may be nil (then all nodes are treated as
 // data-plane healthy — agent gRPC liveness still gates status).
-func NewNodeAPI(store nodes.NodeStore, hub *nodes.Hub, load nodeLoadReader, deriveKey, rulesBaseURL string) *NodeAPI {
-	return &NodeAPI{store: store, hub: hub, load: load, deriveKey: deriveKey, rulesBaseURL: rulesBaseURL}
+func NewNodeAPI(store nodes.NodeStore, hub *nodes.Hub, load nodeLoadReader, deriveKey, rulesBaseURL string, privateSplitDomains []string) *NodeAPI {
+	return &NodeAPI{store: store, hub: hub, load: load, deriveKey: deriveKey,
+		rulesBaseURL: rulesBaseURL, privateSplitDomains: privateSplitDomains}
 }
 
 // dataPlaneHealthy reports the node's last sing-box health (default true when
@@ -315,7 +319,8 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	//    split_cn=1/true → 国内 IP/域名直连(#5);客户端按 smartRoute 偏好传。
 	splitCN := r.URL.Query().Get("split_cn") == "1" || r.URL.Query().Get("split_cn") == "true"
 	cfgJSON, renderErr := BuildClientConfig(node, dpUUID, a.deriveKey,
-		ClientConfigOpts{SplitCN: splitCN, RulesBaseURL: a.rulesBaseURL})
+		ClientConfigOpts{SplitCN: splitCN, RulesBaseURL: a.rulesBaseURL,
+			PrivateSplitDomains: a.privateSplitDomains})
 	if renderErr != nil {
 		slog.Error("connect: build client config failed", "node", nodeUUID, "err", renderErr)
 		apierr.WriteJSON(w, http.StatusInternalServerError, apierr.ErrInternal)
@@ -324,7 +329,8 @@ func (a *NodeAPI) ConnectNode(w http.ResponseWriter, r *http.Request) {
 	// 可观测:国内分流是否真正生效(split_active=两个条件都满足才渲染 rule_set)。
 	slog.Info("client config rendered", "node", nodeUUID, "split_cn", splitCN,
 		"rules_base_set", a.rulesBaseURL != "",
-		"split_active", splitCN && a.rulesBaseURL != "", "bytes", len(cfgJSON))
+		"split_active", splitCN && a.rulesBaseURL != "",
+		"private_split", len(a.privateSplitDomains), "bytes", len(cfgJSON))
 
 	w.Header().Set("Content-Type", "application/json; charset=utf-8")
 	_, _ = w.Write(cfgJSON)