Take the catalogue's composition rules into the node-engine

ADR 0593 §7: the composer with its refusals leaves mesh-sdk, so mesh-sdk
carries no composition rule. The catalogue functions only the
node-engine's composition reaches (Resolve, Resolution's Compose,
Declaration, DataItems, LeftOut, Rules and the rest, the settings,
placeholder and template refusals, the rendering helpers) are copied
with their tests into internal/compose/resolution; a method of a
mesh-sdk shape becomes a function taking it first. The composition
calls its own copies, and the captured catalogue its tests read lives
here now, shared by mesh-compose's tests.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

internal/compose/resolution/busy.go

@@ -0,0 +1,20 @@
+package resolution
+
+import (
+	mcat "git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+// busyInto composes a container's `busy` into the node-engine's words, or takes it away: for an engine that
+// reads it, the command and its timeout written out; for one that does not, the field is not sent, and the
+// container is replaced at once, as before.
+func busyInto(resource map[string]any, with mcat.Rendering) {
+	if _, has := resource[mcat.BusyField]; !has {
+		return
+	}
+	if !with.ReadsBusy {
+		delete(resource, mcat.BusyField)
+		return
+	}
+	b, _, _ := mcat.ReadBusy(resource)
+	resource[mcat.BusyField] = map[string]any{"command": b.Command, "timeout": b.Timeout.String()}
+}