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-core/utils/pluginUtils.d.ts

@@ -0,0 +1,5 @@
+import { WorkboxPlugin } from '../types.js';
+import '../_version.js';
+export declare const pluginUtils: {
+    filter: (plugins: WorkboxPlugin[], callbackName: string) => WorkboxPlugin[];
+};

frontend/node_modules/workbox-core/utils/pluginUtils.js

@@ -0,0 +1,13 @@
+/*
+  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 pluginUtils = {
+    filter: (plugins, callbackName) => {
+        return plugins.filter((plugin) => callbackName in plugin);
+    },
+};

frontend/node_modules/workbox-core/utils/pluginUtils.mjs

@@ -0,0 +1 @@
+export * from './pluginUtils.js';

frontend/node_modules/workbox-core/utils/welcome.d.ts

@@ -0,0 +1 @@
+import '../_version.js';

frontend/node_modules/workbox-core/utils/welcome.js

@@ -0,0 +1,25 @@
+/*
+  Copyright 2019 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 { logger } from '../_private/logger.js';
+import '../_version.js';
+// A WorkboxCore instance must be exported before we can use the logger.
+// This is so it can get the current log level.
+if (process.env.NODE_ENV !== 'production') {
+    const padding = '   ';
+    logger.groupCollapsed('Welcome to Workbox!');
+    logger.log(`You are currently using a development build. ` +
+        `By default this will switch to prod builds when not on localhost. ` +
+        `You can force this with workbox.setConfig({debug: true|false}).`);
+    logger.log(`📖 Read the guides and documentation\n` +
+        `${padding}https://developers.google.com/web/tools/workbox/`);
+    logger.log(`❓ Use the [workbox] tag on Stack Overflow to ask questions\n` +
+        `${padding}https://stackoverflow.com/questions/ask?tags=workbox`);
+    logger.log(`🐛 Found a bug? Report it on GitHub\n` +
+        `${padding}https://github.com/GoogleChrome/workbox/issues/new`);
+    logger.groupEnd();
+}

frontend/node_modules/workbox-core/utils/welcome.mjs

@@ -0,0 +1 @@
+export * from './welcome.js';