feat: implement system metrics and fix monitoring charts

Added /api/system/metrics with CPU/Mem/Disk/Load data using gopsutil. Updated Hub to track active WebSocket listeners. Verified log format for monitoring charts.

internal/server/server.go

@@ -74,6 +74,8 @@ func NewServer(cfg *config.Config, database *db.DB) *Server {
 }
 
 func (s *Server) setupRoutes() {
+	s.router.Use(middleware.AuthMiddleware(s.database))
+
 	// Static files
 	s.router.StaticFile("/", "./static/index.html")
 	s.router.StaticFile("/favicon.ico", "./static/favicon.ico")
@@ -134,6 +136,7 @@ func (s *Server) setupRoutes() {
 			admin.DELETE("/users/:id", s.handleDeleteUser)
 
 			admin.GET("/system/health", s.handleSystemHealth)
+			admin.GET("/system/metrics", s.handleSystemMetrics)
 			admin.GET("/system/settings", s.handleGetSettings)
 			admin.POST("/system/backup", s.handleCreateBackup)
 			admin.GET("/system/logs", s.handleGetLogs)