ci(e2e): use Playwright container for stubbed matrix (#7576)

# Description of Changes

- Use the pinned official Playwright `v1.58.2-noble` container image.
- Remove the per-browser `playwright install --with-deps` step from the
matrix jobs.
- Keep the browser matrix unchanged for independent Chromium, Firefox,
and WebKit reporting.
- Configure Playwright to use the container's root home directory while
directing Docker to a separate configuration path.
- Add npm retry and offline-cache settings to reduce transient
dependency installation failures.

This prevents three matrix jobs from concurrently downloading Playwright
browsers and Linux dependencies, reducing network-related CI failures
while preserving separate per-browser test results.

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

.github/workflows/e2e-stubbed.yml

@@ -14,6 +14,11 @@ jobs:
   playwright-e2e:
     name: playwright-e2e (${{ matrix.browser }})
     runs-on: ubuntu-latest
+    # The image already contains the Playwright browsers and all Linux
+    # dependencies. This keeps the matrix for per-browser reporting while
+    # avoiding three concurrent `playwright install --with-deps` runs.
+    container:
+      image: mcr.microsoft.com/playwright:v1.58.2-noble@sha256:6446946a1d9fd62d9ae501312a2d76a43ee688542b21622056a372959b65d63d
     strategy:
       # One browser breaking must not mask a failure in another - report all.
       fail-fast: false
@@ -40,15 +45,23 @@ jobs:
           cache-dependency-path: frontend/package-lock.json
       - name: Install Task
         uses: go-task/setup-task@01a4adf9db2d14c1de7a560f09170b6e0df736aa # v2.1.0
-      - name: Install Playwright (${{ matrix.browser }})
-        run: task e2e:install -- ${{ matrix.browser }}
       - name: Build frontend (production bundle for vite preview)
         env:
           VITE_BUILD_FOR_PREVIEW: "1"
         run: task frontend:build
       - name: Run stubbed E2E tests (${{ matrix.browser }})
         env:
+          # The official Playwright image expects its browser runtime under
+          # the root home directory. Keep this scoped to Playwright and use a
+          # neutral Docker config path so Docker does not read /root/.docker.
+          HOME: /root
+          DOCKER_CONFIG: /tmp/playwright-docker-config
           PLAYWRIGHT_JSON_OUTPUT_FILE: ${{ github.workspace }}/frontend/playwright-report/results.json
+          NPM_CONFIG_PREFER_OFFLINE: "true"
+          NPM_CONFIG_FETCH_RETRIES: "5"
+          NPM_CONFIG_FETCH_RETRY_FACTOR: "2"
+          NPM_CONFIG_FETCH_RETRY_MINTIMEOUT: "1000"
+          NPM_CONFIG_FETCH_RETRY_MAXTIMEOUT: "120000"
         run: task e2e:stubbed-project PROJECT=${{ matrix.project }} -- --workers=3
       - name: Flag flaky tests
         # Runs regardless of the test outcome: a flaky test (passed on retry)