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/lib/actions/printActions.ts

@@ -0,0 +1,64 @@
+'use server';
+
+import { getDbClient } from '../dbClient';
+import { BillingLocation, Bill } from '../db-types';
+import { AuthenticatedUser } from '../types/next-auth';
+import { withUser } from '../auth';
+import { unstable_noStore as noStore } from 'next/cache';
+
+export interface PrintBarcodeData {
+  locationName: string;
+  billName: string;
+  barcodeImage: string;
+  yearMonth: string;
+}
+
+/**
+ * Fetches all bills with barcode images for a specific month for printing
+ * @param year - Year to fetch data for
+ * @param month - Month to fetch data for (1-12)
+ * @returns Array of barcode data for printing
+ */
+export const fetchBarcodeDataForPrint = withUser(async (user: AuthenticatedUser, year: number, month: number): Promise<PrintBarcodeData[]> => {
+    noStore();
+    
+    const { id: userId } = user;
+    const dbClient = await getDbClient();
+
+    const yearMonth = `${year}-${month.toString().padStart(2, '0')}`;
+
+    // Fetch all locations for the specific month
+    const locations = await dbClient.collection<BillingLocation>("lokacije")
+        .find({
+            userId, // ensure data belongs to authenticated user
+            "yearMonth.year": year,
+            "yearMonth.month": month
+        })
+        .toArray();
+
+    // Extract and flatten barcode data
+    const printData: PrintBarcodeData[] = [];
+    
+    for (const location of locations) {
+        for (const bill of location.bills) {
+            if (bill.barcodeImage && bill.barcodeImage.trim() !== "") {
+                printData.push({
+                    locationName: location.name,
+                    billName: bill.name,
+                    barcodeImage: bill.barcodeImage,
+                    yearMonth: yearMonth
+                });
+            }
+        }
+    }
+
+    // Sort by location name, then by bill name for consistent ordering
+    printData.sort((a, b) => {
+        if (a.locationName !== b.locationName) {
+            return a.locationName.localeCompare(b.locationName);
+        }
+        return a.billName.localeCompare(b.billName);
+    });
+
+    return printData;
+});