feat: implement US-2 - create print route with barcode data fetching

- Add Next.js print route at /[locale]/print/[year]/[month]
- Implement fetchBarcodeDataForPrint function with user authentication
- Create PrintPreview component with basic table layout
- Add proper 404 handling with not-found.tsx
- Fix barcode image display with flexible data URL handling
- Filter and sort bills with barcode data for consistent display

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/ui/PrintPreview.tsx

@@ -0,0 +1,63 @@
+'use client';
+
+import { PrintBarcodeData } from '../lib/actions/printActions';
+
+export interface PrintPreviewProps {
+  data: PrintBarcodeData[];
+  year: number;
+  month: number;
+}
+
+export const PrintPreview: React.FC<PrintPreviewProps> = ({ data, year, month }) => {
+  return (
+    <div className="min-h-screen p-4">
+      <h1 className="text-2xl font-bold mb-4">
+        Print Preview - {year}-{month.toString().padStart(2, '0')}
+      </h1>
+      
+      <div className="mb-4">
+        <p>Found {data.length} barcode(s) for printing</p>
+      </div>
+
+      {/* Basic table structure - will be enhanced in US-3 */}
+      <table className="w-full border-collapse border border-gray-300">
+        <thead>
+          <tr>
+            <th className="border border-gray-300 p-2">Index</th>
+            <th className="border border-gray-300 p-2">Bill Info</th>
+            <th className="border border-gray-300 p-2">Barcode</th>
+          </tr>
+        </thead>
+        <tbody>
+          {data.map((item, index) => (
+            <tr key={`${item.locationName}-${item.billName}`}>
+              <td className="border border-gray-300 p-2">{index + 1}</td>
+              <td className="border border-gray-300 p-2">
+                <div>
+                  <div className="font-medium">{item.yearMonth}</div>
+                  <div>{item.locationName}</div>
+                  <div>{item.billName}</div>
+                </div>
+              </td>
+              <td className="border border-gray-300 p-2">
+                <img 
+                  src={item.barcodeImage.startsWith('data:') ? item.barcodeImage : `data:image/png;base64,${item.barcodeImage}`} 
+                  alt={`Barcode for ${item.billName}`}
+                  className="max-w-full h-auto"
+                />
+              </td>
+            </tr>
+          ))}
+        </tbody>
+      </table>
+      
+      {/* Print button - will be enhanced in US-4 */}
+      <button 
+        onClick={() => window.print()} 
+        className="mt-4 px-4 py-2 bg-blue-500 text-white rounded hover:bg-blue-600"
+      >
+        Print
+      </button>
+    </div>
+  );
+};