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/object-inspect/test/quoteStyle.js

@@ -0,0 +1,26 @@
+'use strict';
+
+var inspect = require('../');
+var test = require('tape');
+
+test('quoteStyle option', function (t) {
+    t['throws'](function () { inspect(null, { quoteStyle: false }); }, 'false is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: true }); }, 'true is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: '' }); }, '"" is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: {} }); }, '{} is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: [] }); }, '[] is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: 42 }); }, '42 is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: NaN }); }, 'NaN is not a valid value');
+    t['throws'](function () { inspect(null, { quoteStyle: function () {} }); }, 'a function is not a valid value');
+
+    t.equal(inspect('"', { quoteStyle: 'single' }), '\'"\'', 'double quote, quoteStyle: "single"');
+    t.equal(inspect('"', { quoteStyle: 'double' }), '"\\""', 'double quote, quoteStyle: "double"');
+
+    t.equal(inspect('\'', { quoteStyle: 'single' }), '\'\\\'\'', 'single quote, quoteStyle: "single"');
+    t.equal(inspect('\'', { quoteStyle: 'double' }), '"\'"', 'single quote, quoteStyle: "double"');
+
+    t.equal(inspect('`', { quoteStyle: 'single' }), '\'`\'', 'backtick, quoteStyle: "single"');
+    t.equal(inspect('`', { quoteStyle: 'double' }), '"`"', 'backtick, quoteStyle: "double"');
+
+    t.end();
+});