feat(currency): centralise money formatting + curated currency picker

New `src/lib/utils/currency.ts` is the single source of truth for
display formatting (`formatCurrency`) and the supported-currency
catalog (`SUPPORTED_CURRENCIES`, 10 codes covering the marina market).

New shared components:
- `<CurrencyInput>` — number input with leading symbol prefix and
  decimal inputMode, raw number value out via onChange.
- `<CurrencySelect>` — Select dropdown over `SUPPORTED_CURRENCIES`
  with symbol + code + label per row, replaces the free-text 3-letter
  inputs that let reps type "EURO" or "$$$" into a 3-char ISO column.

Threaded through every money input + display:
- Forms: berth (price/currency), expense (amount/currency), invoice
  (currency Select + line-items unit-price + step-3 review totals).
- Reads: berth-card / berth-columns / invoice-card / expense-card /
  dashboard KPIs / dashboard revenue-forecast / portal-invoices page.
  Each had its own ad-hoc `Intl.NumberFormat` wrapper with slightly
  different fallbacks; collapsed onto the shared helper.

`InvoiceLineItems` gained a `currency` prop so the unit-price input
prefix and the subtotal use the parent invoice's currency rather than
hard-coded `en-US` formatting.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/utils/currency.ts

@@ -0,0 +1,71 @@
+/**
+ * Single source of truth for money formatting + the supported-currency
+ * dropdown list. Everywhere in the CRM that renders an amount should
+ * call `formatCurrency()` rather than spinning up its own
+ * `Intl.NumberFormat`, and every form that captures an amount should
+ * use the curated `SUPPORTED_CURRENCIES` list rather than a free-text
+ * 3-letter input.
+ */
+
+export const SUPPORTED_CURRENCIES = [
+  { code: 'USD', symbol: '$', label: 'US Dollar' },
+  { code: 'EUR', symbol: '€', label: 'Euro' },
+  { code: 'GBP', symbol: '£', label: 'British Pound' },
+  { code: 'CAD', symbol: 'CA$', label: 'Canadian Dollar' },
+  { code: 'AUD', symbol: 'A$', label: 'Australian Dollar' },
+  { code: 'CHF', symbol: 'CHF', label: 'Swiss Franc' },
+  { code: 'JPY', symbol: '¥', label: 'Japanese Yen' },
+  { code: 'AED', symbol: 'د.إ', label: 'UAE Dirham' },
+  { code: 'SGD', symbol: 'S$', label: 'Singapore Dollar' },
+  { code: 'HKD', symbol: 'HK$', label: 'Hong Kong Dollar' },
+] as const;
+
+export type SupportedCurrencyCode = (typeof SUPPORTED_CURRENCIES)[number]['code'];
+
+const SUPPORTED_SET: ReadonlySet<string> = new Set(SUPPORTED_CURRENCIES.map((c) => c.code));
+
+/**
+ * Format an amount for display. Accepts numbers, numeric strings, and
+ * null/undefined (returns the empty string for the latter so callers
+ * can short-circuit display logic).
+ *
+ * Defaults to `en-US` locale because the CRM is single-locale today;
+ * pass `locale` explicitly when rendering for portal users in the
+ * future. Unknown ISO codes fall through to Intl unchanged so the
+ * function never throws on legacy data.
+ */
+export function formatCurrency(
+  amount: number | string | null | undefined,
+  currency: string | null | undefined = 'USD',
+  options: { locale?: string; minFractionDigits?: number; maxFractionDigits?: number } = {},
+): string {
+  if (amount === null || amount === undefined || amount === '') return '';
+  const value = typeof amount === 'number' ? amount : Number(amount);
+  if (!Number.isFinite(value)) return '';
+  const code = (currency ?? 'USD').toUpperCase();
+  const { locale = 'en-US', minFractionDigits = 2, maxFractionDigits = 2 } = options;
+  try {
+    return new Intl.NumberFormat(locale, {
+      style: 'currency',
+      currency: code,
+      minimumFractionDigits: minFractionDigits,
+      maximumFractionDigits: maxFractionDigits,
+    }).format(value);
+  } catch {
+    // Unknown currency code — degrade to a bare number with the code
+    // appended rather than throwing. Keeps display robust against any
+    // legacy NocoDB rows that smuggled non-ISO strings into the column.
+    return `${value.toFixed(maxFractionDigits)} ${code}`;
+  }
+}
+
+/** Whether a 3-letter code is in the curated supported list. */
+export function isSupportedCurrency(code: string): boolean {
+  return SUPPORTED_SET.has(code.toUpperCase());
+}
+
+/** Symbol for a given currency code, falling back to the code itself. */
+export function currencySymbol(code: string): string {
+  const match = SUPPORTED_CURRENCIES.find((c) => c.code === code.toUpperCase());
+  return match?.symbol ?? code.toUpperCase();
+}