fix(integrations): per-transaction savepoint in Plaid sync_transactions

new_bank_transaction inserts+submits Bank Transactions in a loop within one transaction. On a failed
insert/submit, Postgres poisons the transaction so the except's log_error dies with InFailedSqlTransaction;
MariaDB keeps the Bank Transactions synced before the failure. A full rollback would discard those on
MariaDB too, so wrap each iteration in a savepoint + rollback(save_point=) and re-raise -- preserves
MariaDB's partial-sync behaviour and heals the Postgres txn. The sibling handlers add_institution /
add_bank_accounts were already fixed; this closes the third.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

erpnext/erpnext_integrations/doctype/plaid_settings/plaid_settings.py

@@ -215,7 +215,14 @@ def sync_transactions(bank, bank_account):
 		result = []
 		if transactions:
 			for transaction in reversed(transactions):
-				result += new_bank_transaction(transaction)
+				# per-transaction savepoint: a failed insert/submit must not discard the Bank
+				# Transactions already synced this run (MariaDB keeps them) nor poison the txn on Postgres
+				frappe.db.savepoint("plaid_sync_txn")
+				try:
+					result += new_bank_transaction(transaction)
+				except Exception:
+					frappe.db.rollback(save_point="plaid_sync_txn")
+					raise
 
 		if result:
 			last_transaction_date = frappe.db.get_value("Bank Transaction", result.pop(), "date")