feat: flag Ubuntu phased updates and leave them out of pending counts

apt lists phased updates as upgradable, but an upgrade defers them until the
host is selected. A simulated upgrade names them; they are reported with the
phased flag (vantage-shared v0.6.0) and not counted in pending_after.

internal/sync/sync.go

@@ -406,6 +406,7 @@ func runUpdateCheck(ctx context.Context, cfg *config.Config) {
 				Name:           p.Name,
 				CurrentVersion: p.CurrentVersion,
 				NewVersion:     p.NewVersion,
+				Phased:         p.Phased,
 			}
 		}
 		client, err := grpcclient.New(cfg.ServerURL, cfg.TLS)