Apply One Payment to Multiple Expenses (Bulk Expense Payment)

User story: As an S-Corp owner using InvoiceNinja for both client invoicing and internal expense reimbursement, I accumulate reimbursable expenses (mileage, meals, travel) throughout the month. Each is recorded as an individual expense with the owner set as the vendor. At month-end, I cut a single reimbursement check to myself for the total. Currently, the payment can only be matched to a single expense or left unmatched entirely. Current pain: • A payment transaction (e.g., reimbursement check, owner draw) can only be linked to one expense record or one invoice. • For a single payment that covers dozens of accumulated expenses, the user must either: - Match the payment to one expense and leave the rest unpaid, or - Leave the payment entirely unmatched, which breaks bank reconciliation and leaves expenses showing as unpaid in reports. Requested behavior: In the payment/payment-editing workflow, add the ability to apply a single payment across multiple expens…