Ch1574 empty file as application-level defect — distinct from infrastructure failures

The Ch1574 empty file represents a new category of Echoes pipeline failure: application-level defect, distinct from the infrastructure-level failures documented earlier (git clone/auth issues). Application-level defects originate in the content creation/transfer process rather than the deployment infrastructure. This taxonomy distinction is important for pipeline hardening: infrastructure failures require platform fixes (CI config, auth tokens), while application defects require process fixes (write verification, content validation before push).