docs(mimic-iv): sample query for ICU outtime after deathtime

Complement the transfers audit for mortality-window sensitivity (#1945).

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

Author: Chessing234

mimic-iv/concepts/documentation/icu_outtime_after_deathtime.sql

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+-- ICU stays whose outtime is after the admission deathtime.
+
+SELECT
+  COUNT(*) AS icustays_out_after_death,
+  COUNT(*) FILTER (
+    WHERE ie.outtime > a.deathtime
+      AND ie.outtime <= a.deathtime + INTERVAL '48 hours'
+  ) AS within_48h
+FROM icu.icustays AS ie
+INNER JOIN hosp.admissions AS a
+  ON ie.hadm_id = a.hadm_id
+WHERE a.deathtime IS NOT NULL
+  AND ie.outtime > a.deathtime;