Add PDF417 barcode rendering component

Implements client-side PDF417 barcode rendering with React component.
Uses useEffect to prevent hydration mismatch by generating barcodes
only after component mount. Integrates barcode display in location cards.

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

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

app/lib/pdf/renderBarcode.ts

@@ -0,0 +1,51 @@
+import { BarcodeArray } from './pdf417';
+
+/**
+ * Renders a PDF417 barcode matrix to a canvas and returns it as a data URL.
+ *
+ * This function creates an HTML canvas element, draws the barcode by iterating through
+ * the barcode matrix, and converts the canvas to a base64-encoded PNG data URL that
+ * can be used as an image source.
+ *
+ * @param barcodeMatrix - The barcode array generated by the PDF417 encoder containing
+ *                        the barcode matrix data with dimensions and binary code values
+ * @param blockWidth - The width in pixels of each individual barcode module (bar/space unit)
+ * @param blockHeight - The height in pixels of each individual barcode module (bar/space unit)
+ *
+ * @returns A data URL string (base64-encoded PNG) representing the rendered barcode image,
+ *          suitable for use in an HTML img src attribute
+ *
+ * @example
+ * ```typescript
+ * const pdf417 = createPDF417();
+ * pdf417.init("Hello World", 2, 2);
+ * const barcodeArray = pdf417.getBarcodeArray();
+ * const dataUrl = renderBarcode(barcodeArray, 2, 4);
+ * // dataUrl can now be used: <img src={dataUrl} />
+ * ```
+ */
+export function renderBarcode(barcodeMatrix: BarcodeArray, blockWidth: number, blockHeight: number) {
+  
+  const canvas = document.createElement('canvas');
+  canvas.width = barcodeMatrix.num_cols * blockWidth;
+  canvas.height = barcodeMatrix.num_rows * blockHeight;
+  const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
+
+  let positionY = 0;
+  for (let row = 0; row < barcodeMatrix.num_rows; row += 1) {
+    let positionX = 0;
+
+    for (let col = 0; col < barcodeMatrix.num_cols; col += 1) {
+      if (barcodeMatrix.bcode[row][col] === 1) {
+        ctx.fillStyle = '#000';
+      } else {
+        ctx.fillStyle = '#FFF';
+      }
+      ctx.fillRect(positionX, positionY, blockWidth, blockHeight);
+      positionX += blockWidth;
+    }
+    positionY += blockHeight;
+  }
+
+  return canvas.toDataURL();
+}

app/ui/Pdf417Barcode.tsx

@@ -0,0 +1,50 @@
+'use client';
+
+import { useState, useEffect } from 'react';
+import { generateBarcode } from '../lib/pdf/pdf417';
+import { renderBarcode } from '../lib/pdf/renderBarcode';
+import { EncodePayment } from 'hub-3a-payment-encoder';
+
+export const Pdf417Barcode = () => {
+    const [bitmapData, setBitmapData] = useState<string | undefined>(undefined);
+
+    useEffect(() => {
+
+        const paymentParams = {
+            Iznos:"123,66",  // NOTE: use comma, not period!
+            ImePlatitelja:"Ivan Horvat",
+            AdresaPlatitelja:"Ilica 23",
+            SjedistePlatitelja:"10000 Zagreb",
+            Primatelj:"VODOOPSKRBA I ODV. D.O.O.",
+            AdresaPrimatelja:"FOLNEGOVIĆEVA 1",
+            SjedistePrimatelja:"ZAGREB",
+            IBAN:"HR8924020061100679445",
+            ModelPlacanja: "HR00",  // MUST contain "HR" prefix!
+            PozivNaBroj:"2025-05",
+            SifraNamjene:"",
+            OpisPlacanja:"Budakova Režije",
+        };
+
+        
+        const hub3a_text = EncodePayment(paymentParams);
+
+        const barcodeMatrix = generateBarcode(hub3a_text);
+        const bitmap = renderBarcode(barcodeMatrix, 2, 2);
+        setBitmapData(bitmap);
+    }, []);
+
+    // Don't render until bitmap is generated (prevents hydration mismatch)
+    if (!bitmapData) {
+        return (
+            <div style={{ width: "350px", height: "92px" }} className="flex items-center justify-center">
+                <span className="loading loading-spinner loading-lg"></span>
+            </div>
+        );
+    }
+
+    return (
+        <div>
+            <img src={bitmapData} style={{ width: "350px", height: "92px" }} />
+        </div>
+    );
+}

app/ui/ViewLocationCard.tsx

@@ -6,6 +6,7 @@ import { formatYearMonth } from "../lib/format";
 import { formatCurrency } from "../lib/formatStrings";
 import { useTranslations } from "next-intl";
 import { ViewBillBadge } from "./ViewBillBadge";
+import { Pdf417Barcode } from "./Pdf417Barcode";
 
 export interface ViewLocationCardProps {
     location: BillingLocation
@@ -34,6 +35,7 @@ export const ViewLocationCard:FC<ViewLocationCardProps> = ({location: { _id, nam
                     </p>
                     : null
                 }
+                <Pdf417Barcode />
             </div>
         </div>);
 };