V13-FE-008 — Financial formatter slice note

Requirement: REQ-FE-FORMAT
API/UI/Test: UI-FOUND-08 / T-FE-FMT-01
Source: v60 unit/display-boundary guidance; current frontend/src/shared/formatters/financial.ts.
Assumption: Formatter inputs are already normalized domain values at the FE boundary: currency amount, decimal ratio, quantity, and an instant for as-of display.
Unknown: Per-account currency and locale policy is not part of this Slice.
Decision Required: Quant/QA must approve any future rounding or locale change; formatters must not silently infer units.

Applied boundary

Preserved the existing centralized formatter implementation.
Characterized missing values, explicit currency marker, decimal-to-percent conversion, bounded quantity precision, KST as-of display, and invalid date handling.
No domain calculation, rounding policy, API contract, or database value was changed.

pnpm test -- src/shared/formatters/tests/financial.spec.ts
PASS: 1 file / 5 tests (2026-08-12)

pnpm typecheck
PASS (2026-08-12)

No visual, locale-matrix, or production evidence is claimed.