One runtime principal per node carries every assigned module's tools (hq ADR 0175, to-be 38 WP2.1)

Where the node-tools module is assigned, the machine's bus user list gains one principal of kind
node-tools in place of that module's own: it may subscribe every carried module's tool namespace
and every held seat's verbs on its node, read and follow every membership on its node, call any
tool anywhere, answer what it is asked — and consume nothing, because tools are what it runs.
Every other module keeps its own principal, so a module still serving tools from its container
holds its own credential until it moves.

Named exactly as the module it stands for, so `module issue` and `rollout mint` deliver its
credential through the path a module's already takes, into node-tools' own `broker` secret. The
runtime module's name is one constant in each of the broker and catalogue packages, held to one
string by the agreement test, because a rule turns on it.

cmd/mesh-controller/rollout.go

@@ -346,7 +346,9 @@ func rolloutMint(ctx context.Context, again bool) error {
 			}
 			machines++
 
-		case broker.KindModule:
+		case broker.KindModule, broker.KindNodeTools:
+			// The runtime is minted and delivered exactly as a module is (novox/hq ADR 0175): it is
+			// issued as the module it stands for, to that module's `broker` secret.
 			if p.Module == "mesh-controller" {
 				// The control plane is a module too, and its `broker` secret is the old bus's
 				// credential it is still using while this runs. Writing the new bus's blob there
@@ -365,7 +367,7 @@ func rolloutMint(ctx context.Context, again bool) error {
 				skipped++
 				continue
 			}
-			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusModule, Node: p.Node, Module: p.Module})
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: busKindOf(p.Module), Node: p.Node, Module: p.Module})
 			if err != nil {
 				return err
 			}