Suggested test: copilot/per-output-github-app-override

## Motivation

Link to the gh-aw PR: github/gh-aw#49226 — allows configuring a distinct GitHub App per safe-output handler in `safe-outputs`, instead of one app for the whole workflow.

## Proposed test

- **Workflow file**: `test-copilot-safe-output-github-app.md`
- **Trigger**: `workflow_dispatch`
- **Engine**: copilot
- **Safe output**: `add-comment` with a per-handler `github-app` override (or `create-issue` if simpler to validate)
- **Variant**: standard

## Minimal test prompt sketch

Have the agent add a comment to a known issue/PR via a safe-output configured with its own `github-app` block distinct from the default token, verifying the dedicated `{key}-app-token` step is generated and used.

## New fixtures or secrets needed

May need a second test GitHub App registered with appropriate installation on `githubnext/gh-aw-test` (separate `app-id`/`private-key` secrets) if not already available. If no second app is provisioned, note as blocker and keep as an issue until fixtures exist.

## Notes

Not to be confused with `#6209 Suggested test: copilot/checkout-safe-output-github-app`, which is about checkout token config, not per-handler safe-output app overrides. No open suggestion or existing test currently covers this.

> Generated by [🔍 Suggest New E2E Tests](https://github.com/githubnext/gh-aw-test/actions/runs/30619899301) · aut00 · 18.1 AIC · ⌖ 8.11 AIC · ⊞ 8.3K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-test+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-test%2Fsuggest-new-e2e-tests%22&type=issues)

Start with test-copilot-safe-output-github-app.md and compare the distinction from issue #6209. Add the workflow_dispatch copilot test for a safe-output handler with its own github-app block, then verify the dedicated {key}-app-token step is generated and used; record a blocker if the second test app and secrets are unavailable.

Written by the indexing model from the issue text.