Keep the controller on main's mesh-sdk pin and mint until the grants part takes over, so its impact stays small and no account is minted that the bus it loads refuses (issue 774)

The controller is being removed, so its root module goes back to origin/main's mesh-sdk pin (2da0de7) and
testdata/beside's capture; route-proxy keeps its own pins. Its one functional change stays the account issue:

- Before the grants part's take-over (its key user-list.sealed not saying FollowGrants) the bus loads the
  controller's list, whose hashes come only from its store, so the controller mints as before and hands every
  account it mints, covered or not, to an installed vault at once: no account waits on a node reporting its hash.
- From the take-over it forwards the issue to the vault's issue-account (d791052f) and mints nothing.

And the controller no longer declares or asserts the ASSIGNMENTS stream, which the bus module's tools delete at the
lease write and nothing may make again (research 072 row 33); the verified-sender re-issue stops once it is gone.

Research 072 piece: the gap "vault mints after the lease", the minting piece moves to the vault from the take-over.

cmd/mesh-controller/reissue_verified_sender.go

@@ -207,8 +207,13 @@ func giveVerifiedSendersBack(ctx context.Context, d *doctor) {
 }
 
 // reissueVerifiedSendersOn is reissueVerifiedSenders on the bus: memberships read from the AssignmentsStream and
-// published to it.
+// published to it. Once the stream is gone (the bus module's tools delete it at the lease write, research 072 row 33)
+// the memberships are the grants part's alone, and there is nothing here to issue again.
 func reissueVerifiedSendersOn(ctx context.Context, bus link.OverNATS, records broker.Records, where broker.Placements) int {
+	if _, err := bus.JS.StreamInfo(broker.AssignmentsStream, nats.Context(ctx)); errors.Is(err, nats.ErrStreamNotFound) {
+		fmt.Printf("  the assignments stream is gone: the grants part issues the memberships, none is given a verified sender here\n")
+		return 0
+	}
 	return reissueVerifiedSenders(records, where,
 		func(node, module string) ([]byte, uint64, error) {
 			m, err := bus.JS.GetLastMsg(broker.AssignmentsStream, broker.MembershipSubject(node, module))