feat: add standalone printable invoice page with paper size selection

distribution_fe/app/(print)/invoices/[id]/print/page.tsx

@@ -0,0 +1,68 @@
+'use client'
+
+import { useEffect, useState } from 'react'
+import { useParams } from 'next/navigation'
+import { Button } from '@/components/ui/button'
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from '@/components/ui/select'
+import { InvoiceTemplate, type InvoicePaper } from '@/components/invoice/invoice-template'
+import { useInvoiceDocument } from '@/components/invoice/use-invoice-document'
+
+// Browser page rule per paper size. Receipts are one continuous strip (auto height). Margin is 0 so the
+// browser has no margin area to print its own header/footer (page title, URL, date) into; the sheet pads itself.
+const PAGE_RULE: Record<InvoicePaper, string> = {
+  A4: '@page { size: A4; margin: 0; }',
+  '80mm': '@page { size: 80mm auto; margin: 0; }',
+  '58mm': '@page { size: 58mm auto; margin: 0; }',
+}
+
+// Standalone printable invoice (no dashboard chrome). Opened in a new tab after "Print".
+export default function InvoicePrintPage() {
+  const params = useParams<{ id: string }>()
+  const { invoice, payments, customer, error } = useInvoiceDocument(params.id)
+  const [paper, setPaper] = useState<InvoicePaper>('A4')
+
+  // Open the browser print dialog once, when the invoice first appears.
+  useEffect(() => {
+    if (!invoice) return
+    const t = setTimeout(() => window.print(), 600)
+    return () => clearTimeout(t)
+  }, [invoice])
+
+  if (error) return <p className="p-8 text-sm text-destructive">Failed to load invoice: {error}</p>
+  if (!invoice) return <p className="p-8 text-sm text-muted-foreground">Loading invoice…</p>
+
+  return (
+    <div className="mx-auto max-w-4xl p-6 print:max-w-none print:p-0">
+      <style>{`${PAGE_RULE[paper]} @media print { html, body { background: #fff !important; } }`}</style>
+
+      <div className="mb-4 flex items-center justify-end gap-2 print:hidden">
+        <div className="w-32">
+          <Select value={paper} onValueChange={(v) => setPaper((v as InvoicePaper) ?? 'A4')}>
+            <SelectTrigger><SelectValue placeholder="Paper size" /></SelectTrigger>
+            <SelectContent>
+              <SelectItem value="A4">A4</SelectItem>
+              <SelectItem value="80mm">80mm receipt</SelectItem>
+              <SelectItem value="58mm">58mm receipt</SelectItem>
+            </SelectContent>
+          </Select>
+        </div>
+        <Button type="button" variant="outline" onClick={() => window.close()}>Close</Button>
+        <Button type="button" onClick={() => window.print()}>Print</Button>
+      </div>
+
+      <InvoiceTemplate
+        invoice={invoice}
+        payments={payments}
+        customer={customer}
+        paper={paper}
+        showAgentEdits={invoice.status !== 'Finalized'}
+      />
+    </div>
+  )
+}