agent v0.49.0: reboot-during-backup stale-lock recovery (F2-b) + shared-parent script redeploy fix (F2-a)

F2-b: at startup, recover a guest left with a stale vzdump lock by a
reboot-during-backup — pct unlock -> delete dangling vzdump snapshot ->
start iff onboot, guarded by a no-vzdump-running invariant (fail-safe).
New internal/localapi/stalelock.go; proxmox GuestConfig.Lock()/OnBoot(),
ListSnapshots, ListRunningTasks, Snapshot type. New narrow sudoers grant
FELHOM_STALELOCK (pct unlock) + Critical capability stalelock-unlock.

F2-a: EnsureSharedParent only redeployed the boot script when the UNIT
differed, so the v0.36.6 make-private fix never reached hosts whose unit
was current -> /mnt/felhom-drives stayed in root's shared:1 and doubled
every drive bind. New sharedParentInstallStale compares BOTH script and
unit. Boot-time-only; never churns the live mount.

Both root causes confirmed live on felhom-pve before fixing. Green gate
(build/vet/test) all pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162BnMpUXscPsUB1cU8Tr6K

internal/capability/manifest.go

@@ -97,4 +97,8 @@ var manifest = []Capability{
 	{"controllerswap-inspect", "controller-swap / managed auto-update", "/usr/sbin/pct", []string{"exec", "9201", "--", "docker", "inspect", "-f", "{{.State.Running}}", "felhom-controller"}, true},
 	{"controllerswap-restart", "controller-swap / managed auto-update", "/usr/sbin/pct", []string{"exec", "9201", "--", "systemctl", "restart", "felhom-controller-bootstrap.service"}, true},
 	{"controllerswap-write", "controller-swap / managed auto-update", "/usr/sbin/pct", []string{"exec", "9201", "--", "tee", "/etc/felhom-controller-image"}, true},
+
+	// ---- Stale-lock recovery (FELHOM_STALELOCK, v0.49.0; Critical: a guest stuck behind a stale
+	// reboot-during-backup lock can't start → the customer box stays DOWN until this clears it) ----
+	{"stalelock-unlock", "reboot-during-backup stale-lock recovery", "/usr/sbin/pct", []string{"unlock", "9201"}, true},
 }