FINERACT-2836: Isolate Due Savings Charge Failures

[rhopman]

The Pay Due Savings Charges job previously processed all due charges in one shared transaction. If one account had insufficient funds, the job failed and rolled back successful collections for unrelated accounts. Recurring charges also collected all overdue installments in a single transaction, so failure on a later installment rolled back earlier affordable installments.

This change processes at most one due installment per independent transaction. The job repeatedly invokes the transactional service to collect recurring installments from oldest to newest, stopping that charge on the first failure while continuing to process other due charges. Successfully collected installments remain committed, and failures are recorded with the charge, account, and installment due-date context before the job reports the overall failure.

Tests cover mixed funded and insufficient-balance accounts, installment-level transaction isolation, partial catch-up of recurring charges, continued processing of unrelated charges, successful balance and charge updates, all-success behavior, and prevention of duplicate collection on rerun.

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