Compose mesh-enrolment's grants: its bucket written by it alone, the vault's enrolment verbs called by it alone

ADR 0587 §1-§3 (changing ADR 0561 §5) make mesh-enrolment the only caller of the vault's enrolment-token and
node-account and a caller of sign, and §2 its bucket enrolments read by it and by the grants part as a named reader.
The holder calls the vault through its manifest's invokes, in its own name, as any caller does; while the vault serves
either enrolment verb every other principal is denied both, however wide its grant (a runtime's or an agent's `*`),
as ControllerOnly denies the desk's prompt. The writers table gains the open enrolments (mesh-enrolment) and the
node-logins (the vault), each one writer; NamedReaders names the grants part for enrolments. Golden lists unchanged.
Tested as a subtest of TestTheCopiedComposerComposesAsTheControllers, no new test function.

(issue 774, 774/S41)

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

go/buscompose/users.go

@@ -301,6 +301,13 @@ func Users(r Records) ([]Principal, error) {
 		out = append(out, p)
 	}
 
+	// The vault's enrolment verbs are mesh-enrolment's alone, however wide another's grant (novox/hq ADR 0587 §1).
+	if slices.ContainsFunc(VerbsTheEnrolmentAsksTheVault, func(v SeatVerb) bool { return servesVerb(r, v) }) {
+		for i := range out {
+			out[i].VaultEnrols = true
+		}
+	}
+
 	// The grants part creates the durable consumers the accounts need (novox/hq ADR 0561 §6), by stream and name.
 	if grants >= 0 {
 		out[grants].CreatesConsumers = AccountConsumers(out)