feat(currency): sweep remaining concat call sites to formatCurrency

Builds on the centralised formatter shipped in ee2da8f. Replaces
\`\${currency} \${amount}\` style concatenations across the dashboard
revenue tooltip, command-search invoice/expense fallback labels,
expense-duplicate banner, and the invoice + expense PDF templates.
Drops the duplicate \`currencySymbol\` helper inside expense-pdf.service
in favour of the shared util; the two PDF helpers (renderReceiptHeader,
addReceiptErrorPage) now take a currency code instead of a pre-rendered
symbol so the formatter is the single source for spacing + thousands
separators. Also re-runs Prettier on the files where the prior commit
shipped without it.

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

src/components/dashboard/revenue-breakdown-chart.tsx

@@ -7,6 +7,7 @@ import { EmptyState } from '@/components/shared/empty-state';
 import { ChartCard } from './chart-card';
 import { useRevenue } from './use-analytics';
 import type { DateRange } from '@/lib/services/analytics.service';
+import { formatCurrency } from '@/lib/utils/currency';
 
 interface Props {
   range: DateRange;
@@ -71,9 +72,9 @@ export function RevenueBreakdownChart({ range }: Props) {
                 fontSize: 12,
               }}
               formatter={(value, _name, item) => {
-                const c = (item?.payload as { currency?: string } | undefined)?.currency ?? '';
+                const c = (item?.payload as { currency?: string } | undefined)?.currency ?? 'USD';
                 const num = typeof value === 'number' ? value : Number(value);
-                return [`${num.toLocaleString()} ${c}`, 'Amount'];
+                return [formatCurrency(num, c), 'Amount'];
               }}
             />
             <Bar dataKey="amount" fill="hsl(var(--chart-3))" radius={[4, 4, 0, 0]} />