The sandbox composer carries the module the mesh provides itself

A check that composes with a candidate's own composer (any mesh-host change)
gave it the indexer's manifests alone, and the input carries no catalogue, so
mesh-wireguard (shipped with mesh-sdk, no repository) was missing: "nothing
provides mesh-wireguard / mesh-addressing" on novox for mesh-host #200. Each case
now lays the provided module's manifest over its shelf, as the bus reader does.

Issue 1126.

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

internal/composer/composer.go

@@ -134,6 +134,16 @@ func runCase(r Request, c Case, depth string) (CaseVerdict, error) {
 	if err != nil {
 		return CaseVerdict{}, fmt.Errorf("composer: the case %q: %w", c.Name, err)
 	}
+	// The module the mesh provides itself (the private network) has no repository the indexer reads, so no case carries
+	// it: its manifest comes with mesh-sdk and always wins, as the bus reader has it (frombus readBase). Without it a node
+	// it is assigned to composed nothing (issue 1126, check of mesh-host #200: "nothing provides mesh-wireguard").
+	for _, name := range delivery.ProvidedModules() {
+		m, _, err := delivery.ProvidedManifest(name)
+		if err != nil {
+			return CaseVerdict{}, fmt.Errorf("composer: %w", err)
+		}
+		shelf[name] = m
+	}
 	in.Catalogue = shelf
 	in.Nodes = slices.Clone(in.Nodes)
 	in.Holdings = slices.Clone(in.Holdings)