feat: add ZFS monitoring (#2209)

- track pool capacity, health, I/O, scrub status, and vdev errors
- report dataset usage and correct ZFS filesystem metrics
- add pool charts, detail views, refresh controls, and health alerts
- persist pool details and include ZFS usage in disk alerts
- support configurable detail intervals and legacy agent compatibility

---------

Co-authored-by: hank <hank@henrygd.me>

internal/hub/api.go

@@ -125,6 +125,8 @@ func (h *Hub) registerApiRoutes(se *core.ServeEvent) error {
 	apiAuth.DELETE("/user-alerts", alerts.DeleteUserAlerts)
 	// refresh SMART devices for a system
 	apiAuth.POST("/smart/refresh", h.refreshSmartData).BindFunc(excludeReadOnlyRole)
+	// refresh ZFS pool details for a system
+	apiAuth.POST("/zfs/refresh", h.refreshZfsData).BindFunc(excludeReadOnlyRole)
 	// get systemd service details
 	apiAuth.GET("/systemd/info", h.getSystemdInfo)
 	// /containers routes
@@ -389,3 +391,23 @@ func (h *Hub) refreshSmartData(e *core.RequestEvent) error {
 
 	return e.JSON(http.StatusOK, map[string]string{"status": "ok"})
 }
+
+// refreshZfsData handles POST /api/beszel/zfs/refresh requests
+// Fetches fresh ZFS detail data from the agent and updates the collection
+func (h *Hub) refreshZfsData(e *core.RequestEvent) error {
+	systemID := e.Request.URL.Query().Get("system")
+	if systemID == "" {
+		return e.BadRequestError("Invalid system parameter", nil)
+	}
+
+	system, err := h.sm.GetSystem(systemID)
+	if err != nil || !system.HasUser(e.App, e.Auth) {
+		return e.NotFoundError("", nil)
+	}
+
+	if err := system.FetchAndSaveZfsPools(true); err != nil {
+		return e.InternalServerError("", err)
+	}
+
+	return e.JSON(http.StatusOK, map[string]string{"status": "ok"})
+}