Merge main: the trunk renamed the seats and made them data

Both branches changed the seat set from the same starting point, so every number
collided and every `mesh-*` name existed twice. The trunk's numbers and names win:
this branch's records became 0129/0130 and its migrations 0037/0038, and the
hardcoded rename map gave way to the trunk's `seat_alias` table — a rename is a
row now (ADR 0122), not a recompile.

Three of my checks were wrong and the merge is what showed it:

A seat with an empty protocol is a marker, not an incomplete declaration. Most
node-scoped seats are markers — which module is this machine's packet filter —
and refusing one refused most of the set, the showcase module included. A
mistyped field name is already refused by the parser, so an empty protocol was
written as one deliberately.

A claim on a seat this manifest does not declare is not the parser's to judge. A
module may hold a seat another module declared; that is the whole reason ADR 0126
has callers name the seat and not its provider. Whether the seat exists is a fact
about the catalogue, so the refusal is at registration, where every declaration
is in view.

And a seat may share a name with the provision it delivers. `git`, the npm
registry and the artifact store still do, because renaming a delivering seat
cascades to every consumer requiring it, with a window where a holder stops
resolving mid-flight. The trunk deferred exactly those three on purpose.

Full suite green against a real NATS and store.

internal/broker/agreement_catalogue_test.go

@@ -67,7 +67,7 @@ func TestTheAgreementCheckCatchesASubscriptionThatMatchesNothing(t *testing.T) {
 	// An event published under a seat's name is real even though no module declares it as its own.
 	if bad := Disagreements(nil,
 		[]AConsumer{{Module: "watcher", Consumes: []string{"mesh-artifact-store.image.pushed"}}},
-		[]DeclaredSeat{{Name: "mesh-artifact-store", Emits: []string{"image.pushed"}}}); len(bad) != 0 {
+		[]DeclaredSeat{{Name: "the-artifact-store", Emits: []string{"image.pushed"}}}); len(bad) != 0 {
 		t.Fatalf("an event a seat emits was reported as matching nothing: %v", bad)
 	}
 }