Compose a node's own modules from their builds and read what providers elsewhere serve, so a self-composing node hands moved modules and settles served settings as the controller does (issue 1126)

frombus composed every module from the indexer's raw manifest: no moved module
was handed, so the node stood in for own secrets the vault leaves to the
provisioner (the seed's refusals on all four nodes), and a provider elsewhere
had no config values, so mailu's served domain refused shanks.

- takein: the controller's take-in of a done key (artifacts, launchers, the
  templates archive's texts, Resolve) as one SDK rule; catalogue.Launchers holds
  the launcher rule buildstep now delegates to.
- frombus: each module placed on the composing node, and each kept at another
  build (Scope.KeptAt, a fingerprint), composes from its built manifest; another
  node's modules give the keys their served values fill (Reader.Served).
- buscompose: Declared.Served and Principal.ServedReads grant every node the read
  of exactly those keys of mesh-config_resolved.
- compose.ArtifactStoreAddress: the store as the node's composition routes to it.

go/buscompose/buscompose_test.go

@@ -223,6 +223,31 @@ func TestTheCopiedComposerComposesAsTheControllers(t *testing.T) {
 		if !slices.Contains(perms.Subscribe, VaultSecretChanged) {
 			t.Errorf("node one does not hear the vault's secret-changed: %v", perms.Subscribe)
 		}
+		// And what a module on another node serves from its settings, that key alone (mailu's smtp domain, issue 1126).
+		users, err := Users(Records{Nodes: []string{"one", "two"}, Assigned: map[string][]Declared{
+			"two": {{Module: "mailer", Served: []string{"domain", "not.a.token"}}}}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		get := func(key string) string {
+			return "$JS.API.DIRECT.GET.KV_" + ResolvedBucket + ".$KV." + ResolvedBucket + "." + key
+		}
+		for _, u := range users {
+			if u.Kind != KindNode {
+				continue
+			}
+			perms, err := PermissionsFor(u)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if u.Node == "one" && (!reflect.DeepEqual(u.ServedReads, []string{"two.mailer.domain"}) || !MayPublish(perms, get("two.mailer.domain")) ||
+				MayPublish(perms, get("two.mailer.sitename"))) {
+				t.Errorf("node one reads %v of two's resolved values", u.ServedReads)
+			}
+			if u.Node == "two" && len(u.ServedReads) != 0 {
+				t.Errorf("node two is granted its own served keys apart: %v", u.ServedReads)
+			}
+		}
 	})
 	t.Run("the controller's golden server configuration", func(t *testing.T) {
 		seat := Seat{Name: "telegram-sender", Accepts: []string{"send"}, Emits: []string{"delivered", "failed"}}