- H3: Live currency preview below currency inputs shows the value formatted
with thousands separators (en-US, USD) using Intl.NumberFormat. Skipped
inside matrix cells to keep the Y1 monthly table compact.
- M1: Date inputs now apply min/max bounds. Default window is 1900-01-01 to
2100-12-31; per-field override via FieldConfig.min/max as ISO strings.
- H6: On successful submit, replace the form with a SuccessDestination card
(large checkmark, org name, "Submit another" + "safe to close" affordance).
Prevents accidental duplicate submits from back-button / autofill replay.
- M6: Sticky submit bar respects iOS safe-area-inset-bottom.
FieldRenderer now takes a control prop so the currency preview can subscribe
to its single field via useWatch without re-rendering the whole form.
