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/jake/test/integration/publish_task.js

@@ -0,0 +1,27 @@
+let assert = require('assert');
+let exec = require('child_process').execSync;
+
+const PROJECT_DIR = process.env.PROJECT_DIR;
+const JAKE_CMD = `${PROJECT_DIR}/bin/cli.js`;
+
+suite('publishTask', function () {
+
+  this.timeout(7000);
+
+  test('default task', function () {
+    let out = exec(`${JAKE_CMD} -q publish`).toString().trim();
+    let expected = [
+      'Fetched remote tags.'
+      , 'On branch v0.0'
+      , 'Bumped version number to v0.0.2.'
+      , 'Created package for zerb v0.0.2'
+      , 'Publishing zerb v0.0.2'
+      , './pkg/zerb-v0.0.2.tar.gz'
+      , 'BOOM! Published.'
+      , 'Cleaned up package'
+    ].join('\n');
+    assert.equal(expected, out);
+  });
+
+});
+