docs(mimic-iv): add transfers-after-deathtime audit query

Give researchers a concrete count for the #1945 pattern.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: Chessing234

mimic-iv/concepts/documentation/transfers_after_deathtime.sql

@@ -0,0 +1,11 @@
+-- Count hospital transfers whose intime falls after admissions.deathtime.
+-- Illustrates the #1945 ADT-lag pattern (not a stay_id join failure).
+
+SELECT
+  COUNT(*) AS transfer_rows_after_deathtime,
+  COUNT(DISTINCT t.hadm_id) AS admissions_affected
+FROM hosp.transfers AS t
+INNER JOIN hosp.admissions AS a
+  ON t.hadm_id = a.hadm_id
+WHERE a.deathtime IS NOT NULL
+  AND t.intime > a.deathtime;