Merged in feature/mutable-metadata1 (pull request #221)

M1, M2 and M3 complete

* M1, M2 and M3 complete

* review changes

* docs

* docs

api/queryAPI/documents.go

@@ -126,6 +126,16 @@ func (s *Controllers) GetDocument(ctx echo.Context, id DocumentID, params GetDoc
 	if document.FileSizeBytes != nil {
 		response.FileSizeBytes = document.FileSizeBytes
 	}
+	// Mutable-metadata feature (Milestone 2.3a/2.7): surface the two
+	// new fields directly from the DocumentEnriched service struct.
+	// No follow-up DB call here — the extended GetDocumentEnriched SQL
+	// query already populated both values in the single round-trip.
+	if document.CustomSchemaID != nil {
+		csid := openapi_types.UUID(*document.CustomSchemaID)
+		response.CustomSchemaId = &csid
+	}
+	hasCustomMetadata := document.HasCustomMetadata
+	response.HasCustomMetadata = &hasCustomMetadata
 
 	// Include text record if requested and available
 	if document.TextRecord != nil {