MBA-1428: Transaction submission wizard and status view

[devin-ai-integration]

Summary

Web replacement for keying a TRANFILE record for PORTTRAN: a two-step submission wizard (details → review & confirm) plus a transaction status view, backed by a mock service over a TRNREC.cpy-shaped fixture. Stacked on the MBA-1427 position branch; the transactions nav item is now enabled.

Validation mirrors the COBOL paragraphs rather than inventing new rules:

Check	Source
Portfolio id PORT + 4 digits	PORTVALD 1000-VALIDATE-ID
Portfolio must exist	PORTTRAN 2110-CHECK-PORTFOLIO
Type ∈ BU/SL/TR	PORTTRAN 2120-CHECK-TRANSACTION-TYPE
Quantity > 0; price & amount > 0 except TR	PORTTRAN 2130-CHECK-AMOUNTS
Sell ≤ units held	PORTTRAN 2220-PROCESS-SELL

Digit limits come straight from the copybook (S9(11)V9(4) quantity/price, S9(13)V9(2) amount), so an overflowing amount is rejected before review.

Two BigInt decimal helpers keep COMP-3 precision — no Number anywhere in the money path:

// V9(4) x V9(4) -> V9(2), truncating like an unqualified COMPUTE
multiplyDecimals('325.5', '61.7333') === '20094.18'   // not .19
compareDecimals('99.9999', '100') < 0

The sell-balance check runs before the review step (and again in the service on submit), and treats already-pending sells as encumbered:

availableUnits(portfolioId, investmentId)
  = position.units - Σ pending SELL quantities

Submitted records are written with TRN-STATUS = 'P', stamped date/time/sequence, and settle on the next PORTTRAN run — the list view surfaces P/D/F/R with filters on portfolio, status and type.

Reusable FormField was lifted out of PortfolioFormPage (no behaviour change) so both forms share it.

Jira: https://cog-gtm.atlassian.net/browse/MBA-1428

Screenshots

Submission form with auto-calculated amount:

Review & confirm step:

Status view after submit:

Testing

npm run lint, npm run typecheck, npm run build, npm test (71 tests) all pass. New coverage: amount truncation, validation rules, mock service (unknown portfolio, oversell, pending-sell encumbrance), and a full wizard flow test.

Link to Devin session: https://app.devin.ai/sessions/9b436d246db74e7f91301fb25f38af54

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