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/fast-uri/.github/workflows/package-manager-ci.yml

@@ -0,0 +1,24 @@
+name: package-manager-ci
+
+on:
+  push:
+    branches:
+     - main
+     - next
+     - 'v*'
+    paths-ignore:
+      - 'docs/**'
+      - '*.md'
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - '*.md'
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    permissions:
+      contents: read
+    uses: fastify/workflows/.github/workflows/plugins-ci-package-manager.yml@v6