feat(ws): A3 WebSocket 统一连接管理 — 心跳/注册表/监控/优雅关闭

- 新增 pkg/wshub/manager.go 统一 WebSocket 连接管理器 (WSManager)
- 6 个 WebSocket handler 全部迁移: WebShell/kubectl/PodExec/Audit/Metrics/Pipeline
- 心跳机制: ping(30s) + pong handler + read deadline(60s) 自动检测死连接
- 连接注册表: 元数据(类型/用户/远程地址/连接时间/最后活跃)
- 每用户连接限制 MaxConnsPerUser=15 防资源耗尽
- 监控端点: GET /api/v1/ws/stats + GET /api/v1/ws/connections
- 优雅关闭: CloseAll() 发送 CloseGoingAway 帧并关闭所有连接
- 消除 3 个重复 websocket.Upgrader 变量统一为 WSManager 内部 upgrader
- 6/6 A3 测试通过, 17/17 回归测试通过

backend/controller/ws_pipeline_log.go

@@ -8,6 +8,8 @@ import (
 	"strings"
 	"time"
 
+	"ezops/middleware"
+	"ezops/pkg/wshub"
 	ezredis "ezops/pkg/redis"
 
 	"github.com/gin-gonic/gin"
@@ -15,19 +17,16 @@ import (
 	"gorm.io/gorm"
 )
 
-var wsUpgrader = websocket.Upgrader{
-	CheckOrigin: func(r *http.Request) bool { return true },
-}
-
 // WSPipelineLogHandler WebSocket 流水线日志推流
 type WSPipelineLogHandler struct {
 	db    *gorm.DB
 	cache ezredis.Cache
+	wsMgr *wshub.WSManager
 }
 
 // NewWSPipelineLogHandler 创建 WebSocket 日志处理器
-func NewWSPipelineLogHandler(db *gorm.DB, cache ezredis.Cache) *WSPipelineLogHandler {
-	return &WSPipelineLogHandler{db: db, cache: cache}
+func NewWSPipelineLogHandler(db *gorm.DB, cache ezredis.Cache, wsMgr *wshub.WSManager) *WSPipelineLogHandler {
+	return &WSPipelineLogHandler{db: db, cache: cache, wsMgr: wsMgr}
 }
 
 // StreamLog WebSocket 端点：/ws/pipeline/:runId/log
@@ -39,11 +38,15 @@ func (h *WSPipelineLogHandler) StreamLog(c *gin.Context) {
 		return
 	}
 
-	ws, err := wsUpgrader.Upgrade(c.Writer, c.Request, nil)
+	userID := middleware.GetUserID(c)
+	username := middleware.GetUsername(c)
+
+	ws, info, err := h.wsMgr.Upgrade(c, wshub.TypePipeline, userID, username)
 	if err != nil {
 		return
 	}
-	defer ws.Close()
+	defer h.wsMgr.Unregister(info)
+	h.wsMgr.StartHeartbeat(ws, info)
 
 	logKey := fmt.Sprintf("pipeline:run:%d:logs", uint(runID))
 	ctx := c.Request.Context()