Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

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

frontend/node_modules/workbox-google-analytics/utils/constants.js

@@ -0,0 +1,21 @@
+/*
+  Copyright 2018 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import '../_version.js';
+export const QUEUE_NAME = 'workbox-google-analytics';
+export const MAX_RETENTION_TIME = 60 * 48; // Two days in minutes
+export const GOOGLE_ANALYTICS_HOST = 'www.google-analytics.com';
+export const GTM_HOST = 'www.googletagmanager.com';
+export const ANALYTICS_JS_PATH = '/analytics.js';
+export const GTAG_JS_PATH = '/gtag/js';
+export const GTM_JS_PATH = '/gtm.js';
+export const COLLECT_DEFAULT_PATH = '/collect';
+// This RegExp matches all known Measurement Protocol single-hit collect
+// endpoints. Most of the time the default path (/collect) is used, but
+// occasionally an experimental endpoint is used when testing new features,
+// (e.g. /r/collect or /j/collect)
+export const COLLECT_PATHS_REGEX = /^\/(\w+\/)?collect/;