feat: cash advance

migrations/000088_add_cash_advance_to_spending.up.sql

@@ -0,0 +1,24 @@
+-- Spending paid out of a cash advance points back at it. This is how an advance is
+-- accounted for: the team's purchases and expenses are the settlement, so the advance
+-- itself never carries a copy of what was bought.
+-- RESTRICT rather than SET NULL: dropping an advance that still has spending on it
+-- would leave that spending looking like it came straight out of the drawer.
+ALTER TABLE purchase_orders
+    ADD COLUMN IF NOT EXISTS cash_advance_id UUID;
+
+ALTER TABLE purchase_orders
+    ADD CONSTRAINT fk_purchase_orders_cash_advance
+        FOREIGN KEY (cash_advance_id) REFERENCES cash_advances(id) ON DELETE RESTRICT;
+
+CREATE INDEX IF NOT EXISTS idx_purchase_orders_cash_advance_id
+    ON purchase_orders(cash_advance_id);
+
+ALTER TABLE expenses
+    ADD COLUMN IF NOT EXISTS cash_advance_id UUID;
+
+ALTER TABLE expenses
+    ADD CONSTRAINT fk_expenses_cash_advance
+        FOREIGN KEY (cash_advance_id) REFERENCES cash_advances(id) ON DELETE RESTRICT;
+
+CREATE INDEX IF NOT EXISTS idx_expenses_cash_advance_id
+    ON expenses(cash_advance_id);