ci: Desktop update E2E is advisory via continue-on-error, not by leaving all-checks-pass

tests/ci/test_stable_release_graph.py requires every reusable-workflow
job in all-checks-pass; keep it there and let a red shard show without
failing the gate. Log a resource trail during the run: every shard's
runner died ~2 minutes into seeding on the first CI run with only
'The runner has received a shutdown signal'.

.github/workflows/ci.yaml

@@ -194,7 +194,8 @@ jobs:
     needs: detect
     # apps/desktop/e2e/update: a real install.sh install + packaged Desktop,
     # first run, "Update now" hand-off/relaunch, concurrent-update refusal.
-    # Not in all-checks-pass yet: it joins the required set once it has proven stable on CI.
+    # Advisory until it has proven stable on CI: its shards run with continue-on-error, so a
+    # red shard shows on the PR but does not fail all-checks-pass.
     if: ${{ needs.detect.outputs.python_prod == 'true' || needs.detect.outputs.frontend == 'true' }}
     uses: ./.github/workflows/e2e-desktop-update.yml
 
@@ -313,6 +314,7 @@ jobs:
       - bootstrap-installer
       - e2e-desktop
       - e2e-desktop-core
+      - e2e-desktop-update
       - docs-site
       - history-check
       - contributor-check

.github/workflows/e2e-desktop-update.yml

@@ -28,6 +28,8 @@ jobs:
     name: Desktop install/update E2E (Linux, ${{ matrix.cell }})
     runs-on: ubuntu-latest-32-core
     timeout-minutes: 30
+    # Advisory until stable on CI (see ci.yaml): a red shard does not fail the caller.
+    continue-on-error: true
     strategy:
       fail-fast: false
       # One install per shard (every spec restores it; paths are baked in, so
@@ -75,6 +77,13 @@ jobs:
       - name: Run the update suite under xvfb
         working-directory: apps/desktop
         run: |
+          # Resource trail in the log, so a runner that dies mid-run leaves its last state behind.
+          ( while sleep 20; do
+              echo "::group::resources $(date -u +%T)"
+              df -h / "$RUNNER_TEMP" | tail -n +2; free -g | head -2
+              ps -eo pid,ppid,etimes,rss,args --sort=-rss | head -8 | cut -c1-200
+              echo "::endgroup::"
+            done ) &
           xvfb-run -a --server-args="-screen 0 1280x1024x24" \
             npx playwright test -c e2e/update/playwright.config.ts ${{ matrix.specs }}
         env: