AMQP is not a provision: the bus seat delivers the bus, and the word is refused

Two halves of novox/hq ADR 0131. Migration 0040 moves the mesh-broker row from
`amqp` to `mesh-bus`, so the seat's holder answers for the mesh's bus and not for
the wire protocol the old broker spoke — which is what let only the retiring
broker hold the seat that names the bus. Safe under the current holder: the
control plane composes its own address through the seat by name and the overview
derives holders by name; only registration and provision resolution read the
column. What must not happen in between is re-registering the current holder.

And the parser refuses a manifest that provides or requires `amqp`, each refusal
saying what to do instead: a module reaches the mesh's bus through the sdk and
depends on the seat, not on a protocol. A whole-catalogue test asserts nothing
beside this checkout names it; the three modules that did are removed there.

Two tests that used the old broker as a fixture now use the module that replaces
it or a manifest this package owns.

internal/catalogue/seats_declared_test.go

@@ -121,9 +121,9 @@ func TestTheParserDoesNotJudgeWhatOnlyTheStoreKnows(t *testing.T) {
 	t.Cleanup(func() { UseSeats(was) })
 
 	// A store whose bus seat delivers something this module does provide.
-	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "amqp", Decision: "test"}})
-	raw := []byte(`{"module":"lavinmq","version":"1",` +
-		`"provides":[{"name":"amqp","scope":"mesh"}],` +
+	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "mesh-bus", Decision: "test"}})
+	raw := []byte(`{"module":"a-bus","version":"1",` +
+		`"provides":[{"name":"mesh-bus","scope":"mesh"}],` +
 		`"claims":[{"name":"mesh-broker","scope":"mesh"}]}`)
 
 	m, err := ParseManifest(raw)
@@ -135,12 +135,12 @@ func TestTheParserDoesNotJudgeWhatOnlyTheStoreKnows(t *testing.T) {
 	}
 
 	// And with the store saying the seat delivers something else, registration is what refuses it.
-	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "mesh-bus", Decision: "test"}})
+	UseSeats([]Seat{{Name: "mesh-broker", Scope: ScopeMesh, Delivers: "other-bus", Decision: "test"}})
 	if _, err := ParseManifest(raw); err != nil {
 		t.Fatalf("the parser judged it the second time: %v", err)
 	}
 	got := strings.Join(CatalogueProblems(Shelf{m.Module: m}), "; ")
-	if !strings.Contains(got, `does not provide "mesh-bus"`) {
+	if !strings.Contains(got, `does not provide "other-bus"`) {
 		t.Fatalf("registration did not refuse a holder that cannot answer for the seat: %q", got)
 	}
 }