fix: agente ignora discos squashfs y mountpoints /snap/

Los paquetes snap son loop devices de solo lectura que siempre
reportan 100% de uso. Se excluye el fstype squashfs del monitoreo
de disco y adicionalmente se saltan mountpoints que empiecen con /snap/.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent/main.go

@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	"runtime"
 	"sort"
+	"strings"
 	"time"
 
 	"github.com/shirou/gopsutil/v3/cpu"
@@ -193,6 +194,7 @@ func collectMetrics() (*Metricas, error) {
 			"pstore": true, "securityfs": true, "debugfs": true, "tracefs": true,
 			"autofs": true, "fusectl": true, "configfs": true, "efivarfs": true,
 			"bpf": true, "rpc_pipefs": true, "nsfs": true, "ramfs": true,
+			"squashfs": true, // snap packages: loop devices de solo lectura, siempre 100%
 		}
 		seen := map[string]bool{}
 		parts, _ := disk.Partitions(true)
@@ -209,6 +211,9 @@ func collectMetrics() (*Metricas, error) {
 			if seen[e.mountpoint] || skipFS[e.fstype] {
 				continue
 			}
+			if strings.HasPrefix(e.mountpoint, "/snap/") {
+				continue
+			}
 			d, err := disk.Usage(e.mountpoint)
 			if err != nil || d.Total == 0 {
 				continue