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/selfdep.js

@@ -0,0 +1,42 @@
+let assert = require('assert');
+let exec = require('child_process').execSync;
+
+const PROJECT_DIR = process.env.PROJECT_DIR;
+const JAKE_CMD = `${PROJECT_DIR}/bin/cli.js`;
+
+suite('selfDep', function () {
+
+  this.timeout(7000);
+
+  let origStderrWrite;
+
+  setup(function () {
+    origStderrWrite = process.stderr.write;
+    process.stderr.write = function () {};
+  });
+
+  teardown(function () {
+    process.stderr.write = origStderrWrite;
+  });
+
+  test('self dep const', function () {
+    try {
+      exec(`${JAKE_CMD} selfdepconst`);
+    }
+    catch(e) {
+      assert(e.message.indexOf('dependency of itself') > -1);
+    }
+  });
+
+  test('self dep dyn', function () {
+    try {
+      exec(`${JAKE_CMD} selfdepdyn`);
+    }
+    catch(e) {
+      assert(e.message.indexOf('dependency of itself') > -1);
+    }
+  });
+
+});
+
+