feat: WS handler 接入 SessionManager，main.go 注入依赖 + 健康检查获取活跃会话数

backend/cmd/server/main.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/hhs/camtalk/internal/config"
 	"github.com/hhs/camtalk/internal/logger"
+	"github.com/hhs/camtalk/internal/session"
 	"github.com/hhs/camtalk/internal/ws"
 )
 
@@ -33,6 +34,12 @@ func main() {
 		"addr", cfg.Server.Addr(),
 	)
 
+	// 初始化 Session Manager（MVP 默认内存实现）
+	var sessionMgr session.Manager
+	// TODO: 当 Redis 配置非空时切换为 RedisManager
+	sessionMgr = session.NewMemoryManager(30*time.Minute, 20)
+	defer sessionMgr.(*session.MemoryManager).Stop()
+
 	// Gin 模式
 	if cfg.App.Env == "prod" {
 		gin.SetMode(gin.ReleaseMode)
@@ -44,11 +51,11 @@ func main() {
 	// REST API
 	api := r.Group("/api")
 	{
-		api.GET("/health", healthHandler)
+		api.GET("/health", healthHandler(sessionMgr))
 	}
 
 	// WebSocket
-	r.GET("/ws", ws.ServeWS)
+	r.GET("/ws", ws.ServeWS(sessionMgr))
 
 	// HTTP Server
 	srv := &http.Server{
@@ -82,11 +89,13 @@ func main() {
 }
 
 // healthHandler 健康检查。
-func healthHandler(c *gin.Context) {
-	c.JSON(200, gin.H{
-		"status":          "ok",
-		"version":         "0.1.0",
-		"uptime":          time.Since(startTime).String(),
-		"active_sessions": 0, // TODO: 接入 Session Manager
-	})
+func healthHandler(sessionMgr session.Manager) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		c.JSON(200, gin.H{
+			"status":          "ok",
+			"version":         "0.1.0",
+			"uptime":          time.Since(startTime).String(),
+			"active_sessions": sessionMgr.ActiveCount(),
+		})
+	}
 }