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-routing/RegExpRoute.d.ts

@@ -0,0 +1,32 @@
+import { RouteHandler } from 'workbox-core/types.js';
+import { HTTPMethod } from './utils/constants.js';
+import { Route } from './Route.js';
+import './_version.js';
+/**
+ * RegExpRoute makes it easy to create a regular expression based
+ * {@link workbox-routing.Route}.
+ *
+ * For same-origin requests the RegExp only needs to match part of the URL. For
+ * requests against third-party servers, you must define a RegExp that matches
+ * the start of the URL.
+ *
+ * @memberof workbox-routing
+ * @extends workbox-routing.Route
+ */
+declare class RegExpRoute extends Route {
+    /**
+     * If the regular expression contains
+     * [capture groups]{@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp#grouping-back-references},
+     * the captured values will be passed to the
+     * {@link workbox-routing~handlerCallback} `params`
+     * argument.
+     *
+     * @param {RegExp} regExp The regular expression to match against URLs.
+     * @param {workbox-routing~handlerCallback} handler A callback
+     * function that returns a Promise resulting in a Response.
+     * @param {string} [method='GET'] The HTTP method to match the Route
+     * against.
+     */
+    constructor(regExp: RegExp, handler: RouteHandler, method?: HTTPMethod);
+}
+export { RegExpRoute };