Prepare a draft QuickBooks write-back batch (#2642)

Stores, for review, the exact QuickBooks request of every selected item with its SHA-256, a stable Intuit requestid, and the batch manifest hash that approve and post must present. Nothing is sent to QuickBooks. Named journalEntryIds are kept even when blocked (as blocked items with their reason); a dateFrom/dateTo range adds only eligible entries. sparseUpdates correct an object pulled from QuickBooks (Purchase or Deposit): glAccountId is reverse-mapped to its single QuickBooks account, classId is a QuickBooks Class Id, memo sets the private note. Amounts, dates and the bank/card account are never changed. 422 QUICKBOOKS_WRITEBACK_NOTHING_ELIGIBLE when no item is eligible; 409 when an entry is already held by another batch.