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/crypto-random-string/package.json

@@ -0,0 +1,40 @@
+{
+	"name": "crypto-random-string",
+	"version": "2.0.0",
+	"description": "Generate a cryptographically strong random string",
+	"license": "MIT",
+	"repository": "sindresorhus/crypto-random-string",
+	"author": {
+		"name": "Sindre Sorhus",
+		"email": "sindresorhus@gmail.com",
+		"url": "sindresorhus.com"
+	},
+	"engines": {
+		"node": ">=8"
+	},
+	"scripts": {
+		"test": "xo && ava && tsd"
+	},
+	"files": [
+		"index.js",
+		"index.d.ts"
+	],
+	"keywords": [
+		"random",
+		"string",
+		"text",
+		"id",
+		"identifier",
+		"slug",
+		"salt",
+		"crypto",
+		"strong",
+		"secure",
+		"hex"
+	],
+	"devDependencies": {
+		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
+	}
+}