One bus: the AMQP transport is gone from the controller

The mesh runs on the seat's bus alone (novox/hq ADR 0131, design 28 task 5.5). The old
transport's consume loop, build request, tool ask, management API and account scoping are
deleted, and the bus switch with them; the controller connects to the broker seat and to
nothing else. The store-window tests keep their assertions on a bus-less fake, and the tests
that only made sense for the old transport's in-memory holding go with it.

internal/link/bus.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"github.com/nats-io/nats.go"
-	amqp "github.com/rabbitmq/amqp091-go"
 )
 
 // Bus is what the controller needs of the mesh's bus, **in the mesh's own words rather than a
@@ -39,51 +38,6 @@ type Bus interface {
 
 // --- The bus the mesh runs on today -----------------------------------------------------
 
-// OverCurrent is the bus the mesh runs on today, until the rollout.
-type OverCurrent struct{ Channel *amqp.Channel }
-
-func (b OverCurrent) PublishEvent(ctx context.Context, key, source, node string, body []byte) error {
-	id, err := eventID()
-	if err != nil {
-		return err
-	}
-	return b.Channel.PublishWithContext(ctx, EventsExchange, key, false, false, amqp.Publishing{
-		ContentType:  "application/json",
-		DeliveryMode: amqp.Persistent,
-		MessageId:    id,
-		Timestamp:    time.Now().UTC(),
-		Body:         body,
-		Headers: amqp.Table{
-			"x-event-id":   id,
-			"x-source":     source,
-			"x-node":       node,
-			"x-time":       time.Now().UTC().Format(time.RFC3339),
-			"content-type": "application/json",
-		},
-	})
-}
-
-// AskTool is implemented over the existing reply-queue machinery in ask.go; this seam does not
-// change how it works today.
-func (b OverCurrent) AskTool(ctx context.Context, module, tool string, args []byte, timeout time.Duration) ([]byte, error) {
-	answer, err := Ask(ctx, b.Channel, module, tool, args, timeout)
-	if err != nil {
-		return nil, err
-	}
-	return answer.Result, nil
-}
-
-func (b OverCurrent) PublishDeclaration(ctx context.Context, node string, body []byte) error {
-	// To the queue directly rather than through an exchange: a declaration is for one node, and
-	// routing it by name through a shared exchange would mean a binding per node that nothing
-	// removes when a node is retired.
-	return b.Channel.PublishWithContext(ctx, "", QueueFor(node), false, false, amqp.Publishing{
-		ContentType:  "application/json",
-		DeliveryMode: amqp.Persistent,
-		Body:         body,
-	})
-}
-
 // --- NATS, the bus being built ----------------------------------------------------------------
 
 // OverNATS is the bus as a JetStream context.