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/common/common-ws.go

@@ -22,6 +22,8 @@ const (
 	GetSmartData
 	// Request detailed systemd service info from agent
 	GetSystemdInfo
+	// Request ZFS detail data from agent
+	GetZfsData
 	// Add new actions here...
 )
 
@@ -64,6 +66,10 @@ type DataRequestOptions struct {
 	IncludeDetails bool   `cbor:"1,keyasint"`
 }
 
+type ZfsDataRequest struct {
+	Force bool `cbor:"0,keyasint,omitempty"`
+}
+
 type ContainerLogsRequest struct {
 	ContainerID string `cbor:"0,keyasint"`
 }