Disable browser caching for CSS and JS files

Prevents stale styles/scripts after deployments.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server.js

@@ -34,7 +34,13 @@ const PIPER_OK = existsSync(PIPER_MODEL);
 
 const app = express();
 app.use(express.json({ limit: '15mb' })); // photos for page-scanning are base64 in the JSON body
-app.use(express.static(join(ROOT, 'public')));
+app.use(express.static(join(ROOT, 'public'), {
+  setHeaders(res, filePath) {
+    if (filePath.endsWith('.css') || filePath.endsWith('.js')) {
+      res.setHeader('Cache-Control', 'no-cache');
+    }
+  },
+}));
 
 const docxUpload = multer({ storage: multer.memoryStorage(), limits: { fileSize: 20 * 1024 * 1024 } });