v0.57.0 fixup: wire HostReader into the local-API server (was nil in prod)

buildLocalAPIServer never passed Options.HostReader, so s.host was nil — the
v0.56.0 durableIDForMount raw-mount fallback + the role gate's host classification
silently no-op'd. Wire storage.NewProcHostReader(). This makes the raw-drive
intent/guest-bind resolution actually fire live.

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

cmd/felhom-agent/main.go

@@ -767,6 +767,7 @@ func buildLocalAPIServer(cfg config.Config, px *proxmox.Client, store *backup.St
 		Store:         store,
 		Storage:       observer,
 		DriveTargets:  driveTargets, // Impl-2a: registry+units drives for the /disks view (union w/ Observe storages)
+		HostReader:    storage.NewProcHostReader(), // Impl-2b: durableIDForMount raw-mount fallback + role gate
 		Tokens:        tokens,
 		BackupCadence: cfg.Backup.BackupCadence(),
 		// Disk management (slice 8C): the privileged host surface + the data-bearing wipe gate.