Fix filename format: change from LNNN_YYYY to YYYY_LNNN

Also fixed assignment error where year and number were swapped.

generate_receipt.py

@@ -229,8 +229,13 @@ def main():
     output_dir = Path(args.output_dir)
     output_dir.mkdir(parents=True, exist_ok=True)
     
-    # Generate filename (donation number only, no donor name)
-    filename = f"FJCCV_Receipt_{args.donation_number}.pdf"
+    # Generate filename in format YYYY_LNNN.pdf (e.g., 2026_K001001)
+    parts = args.donation_number.rsplit('-', 1)
+    if len(parts) == 2:
+        number, year = parts
+        filename = f"{year}_{number}.pdf"
+    else:
+        filename = f"{args.donation_number}.pdf"
     output_path = output_dir / filename
     
     # Generate receipt