Let a file resource name a template file in its module's repository

A file's text may live in files/<name> beside the manifest instead of inline,
so modules can move their files out of module.json (ADR 0349 clause 2, issue
654). The build packs files/ into the module's declared archive and reads each
template back from the packed bytes, proven by the digest, into content: the
manifest the mesh holds, composition and the node-engine stay as they are.
module check, the merge gate and module add read templates from the tree beside
the manifest, so a change to a template alone is judged. A file naming both
template and content, a template outside files/, a missing one, and a held
manifest that still names one are refused by name.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/inventory/catalogue.go

@@ -117,6 +117,11 @@ func (i *Inventory) RegisterModule(ctx context.Context, m catalogue.Manifest, fr
 			}
 		}
 	}
+	// **The manifest the mesh holds carries each file's text** (novox/hq ADR 0349 §2): one still naming a template
+	// would compose a file with no text, so it is refused by name — a build by a builder that predates templates.
+	if why := catalogue.HeldTemplateProblem(m); why != "" {
+		return fmt.Errorf("%s is not registered: %s", m.Module, why)
+	}
 	raw, err := json.Marshal(m)
 	if err != nil {
 		return err