A route says the largest body its proxy may carry, and both proxies honour it

The registry's public name is served by the predecessor with a twenty-gigabyte buffering
middleware, because a registry takes image layers in single requests of gigabytes and a
proxy's default turns every push into a 413 the registry never sees. A route contribution
had no way to say so, so the mesh could not take the name over without losing what made it
usable.

The contribution now carries `max-request-body`, a whole positive number of bytes, and the
catalogue holds every route to an agreed vocabulary — label or name, port, and the limit —
refusing a key no proxy reads (a field that parses cleanly and does nothing is a promise
nobody keeps) and a route with no port (unreachable by the proxy it just asked for, found at
parse time rather than in a proxy's log). The mesh's own proxy reads the limit as written,
refuses a body past it as 413 rather than the 502 the transport would have reported, and
skips a route whose limit it cannot read rather than carrying what the module said not to.

The registry's hand-over itself is read from the catalogue beside this checkout: the store
still resolves with no proxy, the gate beside it pulls the store in, contributes the
predecessor's name on the port the node gave it, and locks only the door that faces the
world.

hq ADR 0082/0104, the registry hand-over.

internal/catalogue/manifest.go

@@ -870,6 +870,13 @@ func ParseManifest(raw []byte) (Manifest, error) {
 			// round, and both are better said plainly.
 			problems = append(problems, fmt.Sprintf(
 				"%s contributes nothing to %q; if it only needs one, require it", m.Module, to))
+			continue
+		}
+		if to == RouteProvision {
+			// The one provision whose contribution has an agreed vocabulary (route.go): every
+			// proxy reads the same keys, so a key none of them reads is refused here rather than
+			// carried to a proxy that ignores it.
+			problems = append(problems, routeProblems(m.Module, values)...)
 		}
 	}
 	problems = append(problems, m.Build.problems(m.Module)...)