Splitting a payment across GL accounts previously meant the advanced rule
editor — a table of lines with no feedback until save. The finance team's
actual question is "20% here, 30% there, where does the rest go?", which
needs the remainder visible while you allocate.

- New wizard screen: base amount (pre-filled from the stream's actual
  collection average), member-category scope, progressive allocation with
  the unallocated balance as a running figure plus a proportional bar,
  a mandatory remainder destination, and a live journal-entry preview
  that balances before you can save.
- The wizard's arithmetic mirrors RevenueAllocator exactly — tax off the
  top, fixed lines from the pool, percentages of net-after-fixed — so the
  preview is what actually posts. Verified against the live allocator:
  150,000 → 20%/30%/rest = 30,000 / 45,000 / 75,000, and with 14%
  inclusive VAT = 26,315.79 / 39,473.69 / 65,789.47 on net 131,578.95.
- Wire member_category through resolveRule() with specificity scoring
  (category > branch > payment method), so a working-member split wins
  over the general rule with no extra configuration.
- update() resolves and supersedes only the same-scope rule, and no
  longer reads $memberCategory before assigning it.
- Wizard is now the default action from the mapping list and the
  connection centre; the advanced editor moves behind a ⚙ link.
- Arabic tutorial in docs/معالج-توزيع-المبالغ.md.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>