feat: prepare ARR for controlled public deployment

database/003_finance_zero_night_records.sql

@@ -0,0 +1,25 @@
+-- Permit same-day (zero-night) processed Finance records while preserving exact date arithmetic.
+-- PostgreSQL 15+
+-- Target database: booking_test.
+
+BEGIN;
+
+ALTER TABLE finance.daily_records
+    DROP CONSTRAINT daily_records_dates_and_nights_valid;
+
+ALTER TABLE finance.daily_records
+    ADD CONSTRAINT daily_records_dates_and_nights_valid CHECK (
+        arrival IS NULL
+        OR departure IS NULL
+        OR nights IS NULL
+        OR (
+            departure >= arrival
+            AND nights = departure - arrival
+        )
+    );
+
+COMMENT ON CONSTRAINT daily_records_dates_and_nights_valid
+    ON finance.daily_records IS
+  'Allows processed same-day records with zero nights; rejects negative stays and any date/night mismatch.';
+
+COMMIT;