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/lucide-react/dist/esm/icons/crown.mjs.map

@@ -0,0 +1 @@
+{"version":3,"file":"crown.mjs","sources":["../../../src/icons/crown.ts"],"sourcesContent":["import createLucideIcon from '../createLucideIcon';\nimport { IconNode } from '../types';\n\nexport const __iconNode: IconNode = [\n  [\n    'path',\n    {\n      d: 'M11.562 3.266a.5.5 0 0 1 .876 0L15.39 8.87a1 1 0 0 0 1.516.294L21.183 5.5a.5.5 0 0 1 .798.519l-2.834 10.246a1 1 0 0 1-.956.734H5.81a1 1 0 0 1-.957-.734L2.02 6.02a.5.5 0 0 1 .798-.519l4.276 3.664a1 1 0 0 0 1.516-.294z',\n      key: '1vdc57',\n    },\n  ],\n  ['path', { d: 'M5 21h14', key: '11awu3' }],\n];\n\n/**\n * @component @name Crown\n * @description Lucide SVG icon component, renders SVG Element with children.\n *\n * @preview ![img](data:image/svg+xml;base64,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) - https://lucide.dev/icons/crown\n * @see https://lucide.dev/guide/packages/lucide-react - Documentation\n *\n * @param {Object} props - Lucide icons props and any valid SVG attribute\n * @returns {JSX.Element} JSX Element\n *\n */\nconst Crown = createLucideIcon('crown', __iconNode);\n\nexport default Crown;\n"],"names":[],"mappings":";;;;;;;;;AAGO,CAAA,CAAA,CAAA,CAAA,CAAA,CAAM,UAAA,CAAA,CAAA,CAAuB;AAAA,CAAA,CAClC;AAAA,CAAA,CAAA,CAAA,CACE,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA;AAAA,CAAA,CAAA,CAAA,CACA;AAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CACE,CAAA,EAAG,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA;AAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CACH,GAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA;AAAA,CAAA,CAAA,CAAA,CAAA;AACP,CAAA,CAAA,CACF;AAAA,CAAA,CACA,CAAC,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAQ,CAAA,CAAE,GAAG,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAY,CAAA,CAAA,CAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,GAAU;AAC3C,CAAA;AAaA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAM,KAAA,CAAA,CAAA,CAAQ,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAiB,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,EAAS,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAU,CAAA;;"}