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/data_placed.go

@@ -0,0 +1,31 @@
+package resolution
+
+import (
+	mcat "git.novox.be/novox/mesh-sdk/go/catalogue"
+)
+
+// DataItems is every data item the resolution's modules declare, placed on its node with the rendering given: the text
+// the node-backup holder is handed, read. A module left out of the node's declaration keeps its items, as its data is
+// still on the node (ADR 0262); an item that cannot be placed is said in unplaced and left out.
+func DataItems(r mcat.Resolution, with mcat.Rendering) (items map[string][]mcat.PlacedDataItem, unplaced []string, err error) {
+	left := LeftOut(r, with.Settings, with.Adopted)
+	for module, why := range with.NotPlaced {
+		if _, already := left[module]; !already {
+			left[module] = why
+		}
+	}
+	modules := make([]mcat.Manifest, 0, len(r.Modules))
+	for _, m := range r.Modules {
+		if _, isLeft := left[m.Module]; isLeft {
+			m = backupView(m)
+		}
+		modules = append(modules, m)
+	}
+	text, unplaced, err := seatContributions(modules, mcat.Manifest{}, mcat.BackupSeat+":"+mcat.BackupKindData, with,
+		machineFacts(r, with.Names, with.MeshRange), r.Capabilities)
+	if err != nil {
+		return nil, unplaced, err
+	}
+	items, err = mcat.ParseDataItems(text)
+	return items, unplaced, err
+}