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/manifest.go

@@ -1027,6 +1027,28 @@ func ParseManifest(raw []byte) (Manifest, error) {
 		problems = append(problems, fmt.Sprintf(
 			"%q is not a usable slug: lower-case letters, digits, dashes and dots", m.Slug))
 	}
+	// **`amqp` is not a provision, and not a requirement** (novox/hq ADR 0131). A module that wants
+	// messaging wants the mesh's bus — it emits and consumes through the sdk, which the mesh hands the
+	// bus with the module's own credential — and the bus is whatever holds `mesh-broker`, spoken in
+	// whatever that holder speaks. Naming the old wire protocol asks for a specific server, and the
+	// only one that could answer is the one being retired. Refused here so the word cannot come back
+	// through a manifest.
+	for _, offer := range m.Provides {
+		if offer.Name == "amqp" {
+			problems = append(problems, fmt.Sprintf(
+				"%s provides %q, which is not a provision: the mesh's bus is whatever holds "+
+					"mesh-broker, and a module provides mesh-bus to be it (novox/hq ADR 0131)",
+				m.Module, offer.Name))
+		}
+	}
+	for _, r := range m.Requires {
+		if r == "amqp" {
+			problems = append(problems, fmt.Sprintf(
+				"%s requires %q, which is not a provision: a module reaches the mesh's bus through "+
+					"the sdk, and depends on the mesh-broker seat, not on a protocol (novox/hq ADR 0131)",
+				m.Module, r))
+		}
+	}
 	for _, offer := range m.Provides {
 		p := offer.Name
 		if !name.MatchString(p) {