agent v0.34.0: intermediary mount model — shared parent + host-side attach/detach + reconcile

Replaces the per-drive 'pct set -mpN' bind with ONE permanent parent bind
/mnt/felhom-drives plus host-side felhom-data swaps underneath it (propagates
into the running guest live, no pct, no reboot; C1-immune; confined; fail-closed
when absent). EnsureSharedParent installs a boot unit ordered Before=pve-guests.
ReassertGuestBinds is now a pure host-side reconcile. /disks reports GuestPath +
BoundUnderParent for the controller repoint+gate. Non-hollow tests + companions.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/localapi/server.go

@@ -171,6 +171,10 @@ type Server struct {
 	// tests override it. (DiskInfo.DurableID stays the uuid: storage id — that one feeds /disks/assign.)
 	deviceDurableID func(device string) (string, error)
 
+	// boundCheck reports whether a stable guest path has felhom-data bound under it (intermediary model).
+	// Optional — nil defaults to the real host mount-table read (isHostMountpoint); tests inject a fake.
+	boundCheck func(string) bool
+
 	jobsMu sync.Mutex
 	jobs   map[int]*backupJob // per-guest backup job state (slice 8B)