fix: expose attachment readonly and volume_options in storage:list json

The `storage:list <app> --format json` payload conflated the
attachment's `Readonly` flag and its `VolumeOptions` field into a
single derived `volume_options` string that rendered as `ro`,
`<options>`, or `ro,<options>` depending on which fields were set on
the underlying attachment. That shape is fine for the legacy
`host:container[:options]` text view but it leaves drift-detection
tooling unable to tell whether a `ro` token came from
`Attachment.Readonly == true` or from the operator setting
`Attachment.VolumeOptions = "ro"` directly. The JSON now exposes
`readonly` (boolean) and `volume_options` (string) as separate
omitempty keys populated straight from the attachment, and
`formatStorageListEntry` combines them at format time for the colon-
form text view. `ParseMountPath` was extended in lockstep so callers
of the legacy `host:container:opts` form no longer have to special-
case the `ro` token themselves.

plugins/storage/attachment_test.go

@@ -85,7 +85,8 @@ func TestListAppMountEntriesDockerLocal(t *testing.T) {
 	Expect(rows[0].EntryName).To(Equal("demo-data"))
 	Expect(rows[0].HostPath).To(Equal("/var/lib/dokku/data/storage/demo-data"))
 	Expect(rows[0].ContainerPath).To(Equal("/data"))
-	Expect(rows[0].VolumeOptions).To(Equal("ro"))
+	Expect(rows[0].Readonly).To(BeTrue())
+	Expect(rows[0].VolumeOptions).To(BeEmpty())
 
 	// Run phase shows it too because the attachment includes both phases.
 	runRows, err := ListAppMountEntries("demo", PhaseRun)
@@ -164,11 +165,26 @@ func TestListAppMountEntriesVolumeOptions(t *testing.T) {
 		byPath[row.ContainerPath] = row
 	}
 
+	Expect(byPath["/data"].Readonly).To(BeFalse())
 	Expect(byPath["/data"].VolumeOptions).To(Equal("Z"))
 	Expect(formatStorageListEntry(byPath["/data"])).To(Equal("/var/lib/dokku/data/storage/demo-data:/data:Z"))
 
-	Expect(byPath["/ro"].VolumeOptions).To(Equal("ro,noexec,nosuid"))
+	Expect(byPath["/ro"].Readonly).To(BeTrue())
+	Expect(byPath["/ro"].VolumeOptions).To(Equal("noexec,nosuid"))
 	Expect(formatStorageListEntry(byPath["/ro"])).To(Equal("/var/lib/dokku/data/storage/demo-data:/ro:ro,noexec,nosuid"))
+
+	// The wire shape exposes Readonly and VolumeOptions as separate
+	// keys so external drift-detection tooling can compare them
+	// against the underlying Attachment fields one for one.
+	dataJSON, err := json.Marshal(byPath["/data"])
+	Expect(err).NotTo(HaveOccurred())
+	Expect(string(dataJSON)).To(ContainSubstring(`"volume_options":"Z"`))
+	Expect(string(dataJSON)).NotTo(ContainSubstring(`"readonly"`))
+
+	roJSON, err := json.Marshal(byPath["/ro"])
+	Expect(err).NotTo(HaveOccurred())
+	Expect(string(roJSON)).To(ContainSubstring(`"readonly":true`))
+	Expect(string(roJSON)).To(ContainSubstring(`"volume_options":"noexec,nosuid"`))
 }
 
 func TestListAppMountEntriesPhaseFilter(t *testing.T) {