refactor(server): 会话/访客/设置业务逻辑下沉 internal/service 层，handler 瘦身

- handler 只保留请求绑定、权限检查与响应映射；业务校验顺序、状态码与文案逐字保留
- 新增 service.Error 语义错误，由 handler 统一映射 HTTP 响应
- session 875→361 行、widget 745→321 行、settings 540→73 行
- 自动分配/租户设置(工作时间、欢迎语)/消息校验/黑名单检查/联系方式提取随迁 service 包
- 相关单元测试随迁 service 包，go test ./... 全部通过

server/internal/handler/blacklist.go

@@ -1,8 +1,6 @@
 package handler
 
 import (
-	"crypto/sha256"
-	"encoding/hex"
 	"fmt"
 	"net/http"
 	"strings"
@@ -12,6 +10,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"kefu-cloud/server/internal/middleware"
 	"kefu-cloud/server/internal/model"
+	"kefu-cloud/server/internal/service"
 	"kefu-cloud/server/internal/ws"
 )
 
@@ -19,53 +18,6 @@ type BlacklistHandler struct{}
 
 func NewBlacklistHandler() *BlacklistHandler { return &BlacklistHandler{} }
 
-// normalizeDeviceKey 规范化设备指纹：优先客户端 device_id；否则用 UA 摘要哈希兜底。
-func normalizeDeviceKey(deviceID, userAgent string) string {
-	id := strings.TrimSpace(deviceID)
-	if id != "" {
-		if utf8.RuneCountInString(id) > 64 {
-			id = string([]rune(id)[:64])
-		}
-		return id
-	}
-	ua := strings.TrimSpace(userAgent)
-	if ua == "" {
-		return ""
-	}
-	sum := sha256.Sum256([]byte(strings.ToLower(ua)))
-	return hex.EncodeToString(sum[:])[:32]
-}
-
-// isBlacklisted 检查租户下 IP/设备是否在有效黑名单中。
-func isBlacklisted(tenantID uint, kind, value string) (bool, *model.BlacklistEntry) {
-	value = strings.TrimSpace(value)
-	if value == "" || (kind != "ip" && kind != "device") {
-		return false, nil
-	}
-	now := time.Now()
-	var entry model.BlacklistEntry
-	err := model.DB.
-		Where("tenant_id = ? AND kind = ? AND value = ?", tenantID, kind, value).
-		Where("expires_at IS NULL OR expires_at > ?", now).
-		Order("id desc").
-		First(&entry).Error
-	if err != nil {
-		return false, nil
-	}
-	return true, &entry
-}
-
-// checkVisitorBlacklist 同时检查 IP 与设备。
-func checkVisitorBlacklist(tenantID uint, ip, deviceKey string) (blocked bool, kind string, reason string) {
-	if ok, e := isBlacklisted(tenantID, "ip", ip); ok {
-		return true, "ip", e.Reason
-	}
-	if ok, e := isBlacklisted(tenantID, "device", deviceKey); ok {
-		return true, "device", e.Reason
-	}
-	return false, "", ""
-}
-
 type CreateBlacklistReq struct {
 	// SessionID 从会话一键拉黑时必填（自动带出 IP/设备）
 	SessionID *uint `json:"session_id"`
@@ -163,8 +115,9 @@ func (h *BlacklistHandler) Create(c *gin.Context) {
 	var customerID *uint
 
 	if req.SessionID != nil && *req.SessionID > 0 {
-		s, ok := loadTenantSession(c, fmt.Sprintf("%d", *req.SessionID))
-		if !ok {
+		s, err := service.LoadTenantSession(fmt.Sprintf("%d", *req.SessionID), middleware.GetTenantID(c))
+		if err != nil {
+			respondServiceError(c, err)
 			return
 		}
 		session = s
@@ -182,7 +135,7 @@ func (h *BlacklistHandler) Create(c *gin.Context) {
 			value = strings.TrimSpace(s.DeviceKey)
 			if value == "" {
 				// 旧会话兜底：用 UA 哈希
-				value = normalizeDeviceKey("", s.UserAgent)
+				value = service.NormalizeDeviceKey("", s.UserAgent)
 			}
 			if value == "" {
 				c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "该会话无设备标识，无法按设备拉黑"})
@@ -250,7 +203,7 @@ func (h *BlacklistHandler) Create(c *gin.Context) {
 		if kind == "device" {
 			kindLabel = "设备"
 		}
-		detail := userDisplayName(operatorID) + " 拉黑" + kindLabel + " " + maskBlacklistValue(kind, value) +
+		detail := service.UserDisplayName(operatorID) + " 拉黑" + kindLabel + " " + maskBlacklistValue(kind, value) +
 			"（" + durationLabel(req.Duration) + "）：" + reason
 		model.DB.Create(&model.SessionEvent{
 			SessionID:  session.ID,
@@ -274,12 +227,12 @@ func (h *BlacklistHandler) Create(c *gin.Context) {
 				Action:     "end",
 				Detail:     "结束会话: 拉黑访客",
 			})
-			broadcastSessionUpdate(session)
+			service.BroadcastSessionUpdate(session)
 			if payload, err := ws.NewEvent("session_updated", session.ID, session); err == nil {
 				ws.DefaultHub.BroadcastToSession(session.TenantID, session.ID, session.AgentID, payload)
 			}
 		} else {
-			broadcastSessionUpdate(session)
+			service.BroadcastSessionUpdate(session)
 		}
 	}