Enable extended PR screening for external PRs

Opts in to the new PR screening features in the shared triage workflow:
- Instantly closes PRs with zero file changes
- Detects same-author resubmissions of recently closed PRs
- Fast-tracks small, well-described fixes to ready-for-review
- Accelerates closure of large unsolicited PRs (3 days vs 7)

Depends on desktop/gh-cli-and-desktop-shared-workflows#17

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/triage-pull-requests.yml

@@ -31,6 +31,10 @@ jobs:
       github.event_name == 'pull_request_target' &&
       (github.event.action == 'opened' || github.event.action == 'reopened' || github.event.action == 'edited')
     uses: desktop/gh-cli-and-desktop-shared-workflows/.github/workflows/triage-pr-requirements.yml@main
+    with:
+      enable_pr_screening: true
+      days_until_close: 4
+      large_pr_days_until_close: 2
     permissions:
       issues: read
       pull-requests: write
@@ -38,6 +42,10 @@ jobs:
   close-unmet-requirements:
     if: github.event_name == 'schedule'
     uses: desktop/gh-cli-and-desktop-shared-workflows/.github/workflows/triage-pr-requirements.yml@main
+    with:
+      enable_pr_screening: true
+      days_until_close: 4
+      large_pr_days_until_close: 2
     permissions:
       issues: read
       pull-requests: write