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/resolve/test/dotdot.js

@@ -0,0 +1,29 @@
+var path = require('path');
+var test = require('tape');
+var resolve = require('../');
+
+test('dotdot', function (t) {
+    t.plan(4);
+    var dir = path.join(__dirname, '/dotdot/abc');
+
+    resolve('..', { basedir: dir }, function (err, res, pkg) {
+        t.ifError(err);
+        t.equal(res, path.join(__dirname, 'dotdot/index.js'));
+    });
+
+    resolve('.', { basedir: dir }, function (err, res, pkg) {
+        t.ifError(err);
+        t.equal(res, path.join(dir, 'index.js'));
+    });
+});
+
+test('dotdot sync', function (t) {
+    t.plan(2);
+    var dir = path.join(__dirname, '/dotdot/abc');
+
+    var a = resolve.sync('..', { basedir: dir });
+    t.equal(a, path.join(__dirname, 'dotdot/index.js'));
+
+    var b = resolve.sync('.', { basedir: dir });
+    t.equal(b, path.join(dir, 'index.js'));
+});