feat: enhance metrics collection with disk and network I/O rates, and update frontend to display new data

server.go

@@ -16,9 +16,11 @@ import (
 )
 
 func runServer(port int) {
-	_, cancel := context.WithCancel(context.Background())
+	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
+	streamSys := backend.NewSysInfoHeadless(ctx)
+
 	mux := http.NewServeMux()
 
 	// GET /api/metrics — latest snapshot
@@ -61,7 +63,7 @@ func runServer(port int) {
 			case <-r.Context().Done():
 				return
 			case <-ticker.C:
-				m, err := backend.CollectFull(r.Context())
+				m, err := streamSys.Snapshot()
 				if err != nil {
 					continue
 				}