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/invoices/invoice-line-items.tsx

@@ -112,9 +112,7 @@ export function InvoiceLineItems({ name = 'lineItems', currency = 'USD' }: Invoi
           type="button"
           variant="outline"
           size="sm"
-          onClick={() =>
-            append({ description: '', quantity: 1, unitPrice: 0 })
-          }
+          onClick={() => append({ description: '', quantity: 1, unitPrice: 0 })}
         >
           <Plus className="mr-1.5 h-3.5 w-3.5" />
           Add Line Item