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/NavigationRoute.d.ts

@@ -0,0 +1,63 @@
+import { RouteHandler } from 'workbox-core/types.js';
+import { Route } from './Route.js';
+import './_version.js';
+export interface NavigationRouteMatchOptions {
+    allowlist?: RegExp[];
+    denylist?: RegExp[];
+}
+/**
+ * NavigationRoute makes it easy to create a
+ * {@link workbox-routing.Route} that matches for browser
+ * [navigation requests]{@link https://developers.google.com/web/fundamentals/primers/service-workers/high-performance-loading#first_what_are_navigation_requests}.
+ *
+ * It will only match incoming Requests whose
+ * {@link https://fetch.spec.whatwg.org/#concept-request-mode|mode}
+ * is set to `navigate`.
+ *
+ * You can optionally only apply this route to a subset of navigation requests
+ * by using one or both of the `denylist` and `allowlist` parameters.
+ *
+ * @memberof workbox-routing
+ * @extends workbox-routing.Route
+ */
+declare class NavigationRoute extends Route {
+    private readonly _allowlist;
+    private readonly _denylist;
+    /**
+     * If both `denylist` and `allowlist` are provided, the `denylist` will
+     * take precedence and the request will not match this route.
+     *
+     * The regular expressions in `allowlist` and `denylist`
+     * are matched against the concatenated
+     * [`pathname`]{@link https://developer.mozilla.org/en-US/docs/Web/API/HTMLHyperlinkElementUtils/pathname}
+     * and [`search`]{@link https://developer.mozilla.org/en-US/docs/Web/API/HTMLHyperlinkElementUtils/search}
+     * portions of the requested URL.
+     *
+     * *Note*: These RegExps may be evaluated against every destination URL during
+     * a navigation. Avoid using
+     * [complex RegExps](https://github.com/GoogleChrome/workbox/issues/3077),
+     * or else your users may see delays when navigating your site.
+     *
+     * @param {workbox-routing~handlerCallback} handler A callback
+     * function that returns a Promise resulting in a Response.
+     * @param {Object} options
+     * @param {Array<RegExp>} [options.denylist] If any of these patterns match,
+     * the route will not handle the request (even if a allowlist RegExp matches).
+     * @param {Array<RegExp>} [options.allowlist=[/./]] If any of these patterns
+     * match the URL's pathname and search parameter, the route will handle the
+     * request (assuming the denylist doesn't match).
+     */
+    constructor(handler: RouteHandler, { allowlist, denylist }?: NavigationRouteMatchOptions);
+    /**
+     * Routes match handler.
+     *
+     * @param {Object} options
+     * @param {URL} options.url
+     * @param {Request} options.request
+     * @return {boolean}
+     *
+     * @private
+     */
+    private _match;
+}
+export { NavigationRoute };