- Add document_templates pgTable with 7 columns: id, name, formTemplateId, signatureFields, archivedAt, createdAt, updatedAt - formTemplateId FK references formTemplates.id with no onDelete cascade - signatureFields typed as SignatureFieldData[] via jsonb, nullable (template starts empty) - archivedAt nullable timestamp for soft-delete (NULL = active) - Add documentTemplatesRelations joining to formTemplates