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/snail.mjs.map

@@ -0,0 +1 @@
+{"version":3,"file":"snail.mjs","sources":["../../../src/icons/snail.ts"],"sourcesContent":["import createLucideIcon from '../createLucideIcon';\nimport { IconNode } from '../types';\n\nexport const __iconNode: IconNode = [\n  ['path', { d: 'M2 13a6 6 0 1 0 12 0 4 4 0 1 0-8 0 2 2 0 0 0 4 0', key: 'hneq2s' }],\n  ['circle', { cx: '10', cy: '13', r: '8', key: '194lz3' }],\n  ['path', { d: 'M2 21h12c4.4 0 8-3.6 8-8V7a2 2 0 1 0-4 0v6', key: 'ixqyt7' }],\n  ['path', { d: 'M18 3 19.1 5.2', key: '9tjm43' }],\n  ['path', { d: 'M22 3 20.9 5.2', key: 'j3odrs' }],\n];\n\n/**\n * @component @name Snail\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/snail\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 Snail = createLucideIcon('snail', __iconNode);\n\nexport default Snail;\n"],"names":[],"mappings":";;;;;;;;;AAGO,CAAA,CAAA,CAAA,CAAA,CAAA,CAAM,UAAA,CAAA,CAAA,CAAuB;AAAA,CAAA,CAClC,CAAC,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAQ,CAAA,CAAE,GAAG,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,CAAoD,CAAA,CAAA,CAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,GAAU,CAAA;AAAA,CAAA,CACjF,CAAC,QAAA,CAAA,CAAU,CAAA,CAAE,EAAA,CAAA,CAAI,CAAA,CAAA,CAAA,CAAA,EAAM,CAAA,CAAA,CAAA,CAAI,IAAA,CAAA,CAAM,CAAA,EAAG,CAAA,CAAA,CAAA,CAAA,CAAK,GAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,EAAU,CAAA;AAAA,CAAA,CACxD,CAAC,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAQ,CAAA,CAAE,GAAG,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,CAA8C,CAAA,CAAA,CAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,GAAU,CAAA;AAAA,CAAA,CAC3E,CAAC,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAQ,CAAA,CAAE,GAAG,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAkB,CAAA,CAAA,CAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,GAAU,CAAA;AAAA,CAAA,CAC/C,CAAC,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAQ,CAAA,CAAE,GAAG,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAkB,CAAA,CAAA,CAAA,CAAA,CAAK,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,CAAA,GAAU;AACjD,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;;"}