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/upath/package.json

@@ -0,0 +1,60 @@
+{
+  "name": "upath",
+  "description": "A proxy to `path`, replacing `\\` with `/` for all results & new methods to normalize & join keeping leading `./` and add, change, default, trim file extensions.",
+  "version": "1.2.0",
+  "homepage": "http://github.com/anodynos/upath/",
+  "author": {
+    "name": "Angelos Pikoulas",
+    "email": "agelos.pikoulas@gmail.com"
+  },
+  "license": "MIT",
+  "keywords": [
+    "path",
+    "unix",
+    "windows",
+    "extension",
+    "file extension",
+    "replace extension",
+    "change extension",
+    "trim extension",
+    "add extension",
+    "default extension"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/anodynos/upath"
+  },
+  "bugs": {
+    "url": "http://github.com/anodynos/upath/issues",
+    "email": "agelos.pikoulas@gmail.com"
+  },
+  "main": "./build/code/upath.js",
+  "types": "./upath.d.ts",
+  "preferGlobal": false,
+  "scripts": {
+    "test": "grunt",
+    "build": "grunt lib"
+  },
+  "directories": {
+    "doc": "./doc",
+    "dist": "./build"
+  },
+  "engines": {
+    "node": ">=4",
+    "yarn": "*"
+  },
+  "devDependencies": {
+    "chai": "~4.0.2",
+    "coffee-script": "1.12.6",
+    "grunt": "0.4.5",
+    "grunt-contrib-watch": "^1.1.0",
+    "grunt-urequire": "0.7.x",
+    "lodash": "^4.17.15",
+    "mocha": "~3.4.2",
+    "uberscore": "0.0.19",
+    "underscore.string": "^3.3.5",
+    "urequire": "0.7.0-beta.33",
+    "urequire-ab-specrunner": "^0.2.5",
+    "urequire-rc-inject-version": "^0.1.6"
+  }
+}