AMQP is a provision, not the bus

0117 went a step further than it had grounds for. It was right that the bus
is the only bus, and wrong that the amqp interface must therefore retire —
because it conflated two reasons to want a broker. Using one to reach
another module is a second bus and stays refused. Needing an AMQP broker as
a backing service, the way something needs a database, is ordinary, and
forbidding it would make the mesh unable to run normal software while
calling that architecture.

So the broker becomes a plain provider module: no seat, not foundation,
never raised at genesis, no retirement condition. lavinmq now claims nothing
and provides amqp; nats claims mesh-broker and provides nothing.

The rule that survives is about direction, not software: inter-module
communication goes over the bus. A module may hold a broker for itself; it
may not use one as a channel to another module. That is a review judgement
where 0117 could have used a parser, which is the honest cost.

0106's progressive insight was itself wrong and is corrected by a second one
there — nothing moves off the old broker, so its "one purpose" sentence does
not become true, it is just not what that server is.

The insight check needed two fixes it found itself: a date may carry
trailing words, and a bold run with a link is discussing an insight rather
than marking one. All four bad shapes still fire.

02-DECISIONS/README.md

@@ -133,7 +133,8 @@ python3 00-META/checks/index.py            fail if stale
 - **0105** — [The mesh adopts the predecessor's tunnel in place](0105-the-mesh-adopts-the-predecessors-tunnel-in-place.md)
 - **0106** — [The bus is NATS](0106-the-bus-is-nats.md)
 - **0116** — [The bus is built in five steps, and the protocol moves with it](0116-the-bus-is-built-in-five-steps.md)
-- **0117** — [The bus is the only broker](0117-the-bus-is-the-only-broker.md)
+- **0117** — [The bus is the only broker](0117-the-bus-is-the-only-broker.md)  *(superseded)*
+- **0119** — [AMQP is a provision, not the bus](0119-amqp-is-a-provision-not-the-bus.md)
 
 ### Its tiers, from the bottom up