refactor: replace exceljs with write-excel-file for analytics export

exceljs (latest 4.4.0) ships years-old transitive dependencies that
npm flags as deprecated on every install (rimraf 2, glob 7, inflight,
fstream, lodash.isequal) and needed a uuid override for a security
advisory. It was only used for the single-sheet analytics XLSX export,
which write-excel-file covers with the same output (column widths,
bold/grey header, formula-injection escaping).

Removes the now-unneeded exceljs uuid override.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package.json

@@ -19,7 +19,6 @@
     "concurrently": "^9.0.0",
     "cors": "^2.8.5",
     "dotenv": "^17.3.1",
-    "exceljs": "^4.4.0",
     "express": "^5.2.1",
     "express-rate-limit": "^8.5.2",
     "flatpickr": "^4.6.13",
@@ -38,6 +37,7 @@
     "react-hot-toast": "^2.4.0",
     "react-router-dom": "^7.15.1",
     "uuid": "^14.0.0",
+    "write-excel-file": "^4.1.1",
     "xml2js": "^0.6.0"
   },
   "devDependencies": {
@@ -49,11 +49,6 @@
     "tailwindcss": "^4.3.0",
     "vite": "^8.0.0"
   },
-  "overrides": {
-    "exceljs": {
-      "uuid": "^11.1.1"
-    }
-  },
   "allowScripts": {
     "better-sqlite3@12.11.1": true
   }

server/routes/analytics.js

@@ -1,6 +1,6 @@
 import { Router, json } from 'express';
 import crypto from 'crypto';
-import ExcelJS from 'exceljs';
+import writeXlsxFile from 'write-excel-file/node';
 import PDFDocument from 'pdfkit';
 import { getDb } from '../config/database.js';
 import { authenticateToken } from '../middleware/auth.js';
@@ -246,26 +246,24 @@ router.get('/:id/export/:format', authenticateToken, async (req, res) => {
 
     if (format === 'xlsx') {
       // Prefix-escape strings that would otherwise be evaluated as formulas.
-      const sanitizeXlsx = (r) => {
+      const sanitizeXlsx = (v) =>
-        const out = {};
+        (typeof v === 'string' && /^[=+\-@\t\r]/.test(v)) ? "'" + v : v;
-        for (const k of Object.keys(r)) {
+
-          const v = r[k];
+      const headerRow = COLUMNS.map(c => ({
-          out[k] = (typeof v === 'string' && /^[=+\-@\t\r]/.test(v)) ? "'" + v : v;
+        value: c.header,
-        }
+        fontWeight: 'bold',
-        return out;
+        backgroundColor: '#e0e0e0',
-      };
+      }));
-      const workbook = new ExcelJS.Workbook();
+      const dataRows = rows.map(r => COLUMNS.map(c => ({ value: sanitizeXlsx(r[c.key]) })));
-      const sheet = workbook.addWorksheet('Analytics');
+
-      sheet.columns = COLUMNS;
+      const buffer = await writeXlsxFile([headerRow, ...dataRows], {
-      rows.forEach(r => sheet.addRow(sanitizeXlsx(r)));
+        columns: COLUMNS.map(c => ({ width: c.width })),
-      // Style header row
+        sheet: 'Analytics',
-      sheet.getRow(1).font = { bold: true };
+      }).toBuffer();
-      sheet.getRow(1).fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE0E0E0' } };
 
       res.setHeader('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
       res.setHeader('Content-Disposition', `attachment; filename="${safeName}.xlsx"`);
-      await workbook.xlsx.write(res);
+      return res.send(buffer);
-      return res.end();
     }
 
     if (format === 'pdf') {