Do not let unknown POD status reopen delivery-completion calls

When a voice workflow has separate delivery-completion and proof-of-delivery follow-ups, track physical completion independently from document status. A verified caller can confirm freight unloaded and the driver released while POD remains unknown. If the completion suppression predicate also requires POD to be non-null, it can keep ordinary completion calls eligible after physical completion is already established. Preserve the known physical milestones and route any genuinely needed document collection through its own policy. This is a predicate-level failure mechanism; it does not establish that every unknown POD warrants a phone call or that arrival alone means delivery is complete. Applies when: Completion calls repeat after verified unloading and release while POD status is missing. Keywords: voice scheduler delivery completion POD suppression milestones followup predicate