v0.56.0: resolve a raw enrolled drive's durable-id from the mount table

durableIDForMount was Observe-only, so a raw (non-PVE-storage) drive's enroll
intent + guest-bind went unrecorded ("durable-id unresolved") — it mounted+bound
but wasn't intent-tracked (RegistryKnownTargets skips intent==new). Fall back to
resolving the mount's device fs-UUID (HostReader.Mounts + ResolveUUID) →
uuid:<fs-uuid>, same scheme as Observe. Test + red-proof. Residual:
ReassertGuestBinds still Observe-based (raw guest-bind not re-asserted post-reboot).

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

cmd/felhom-agent/main.go

@@ -45,7 +45,7 @@ import (
 
 // version is the agent version. Overridable at build time with
 // -ldflags "-X main.version=<v>"; defaults to the in-repo CHANGELOG version.
-var version = "0.55.0"
+var version = "0.56.0"
 
 // runGuestHook is the PVE pre-start hook body (`felhom-agent guest-hook <vmid> <phase>`). On the
 // pre-start phase it creates placeholder dirs for any absent bind-mount source so the guest always boots