Suggested test: copilot/nested-imports-dependency-order

## Motivation

github/gh-aw#57746 — "Fix dependency ordering and cycle detection for nested imports" fixed a bug where nested imported `steps:` merged in BFS order instead of dependency order, and cross-subdirectory import cycles were not detected. No regression test exists for this in `gh-aw-test`.

## Proposed test

- **Workflow file**: `test-copilot-nested-imports-order.md` plus supporting import fixtures (e.g. `test-copilot-nested-imports-order.dep.md`, `.lib.md` in the same directory)
- **Trigger**: `workflow_dispatch`
- **Engine**: copilot
- **Safe output**: `create-issue` (used only to prove the compiled/merged steps ran in the correct order, e.g. by embedding an order-marker in the issue body)
- **Variant**: standard

## Minimal test prompt sketch

Two or three tiny imported `.md` fragments each contributing a `pre-agent-steps` entry that appends a marker to a step output or env var; the main workflow imports them nested (A imports B imports C). The agent prompt reads the accumulated marker sequence and creates an issue whose body encodes the observed order, which the harness checks matches the expected dependency order (C before B before A).

## New fixtures or secrets needed

Requires 2–3 new small `.md` import-fragment files alongside the main test workflow (not currently present anywhere in this repo — no `shared/` or import fixtures directory exists yet for main-repo tests). No new secrets.

## Notes

This is compiler-level behavior (import resolution), somewhat orthogonal to safe-outputs test conventions here, so flagging as an issue to confirm the fixture-file approach is acceptable before writing it, rather than assuming and submitting a PR.

> Generated by [🔍 Suggest New E2E Tests](https://github.com/githubnext/gh-aw-test/actions/runs/33609783863) · copilot · auto · 83.2 AIC · ⌖ 8.02 AIC · ⊞ 8.8K · [◷](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 by reviewing existing gh-aw-test workflow files and safe-output test conventions, then inspect the proposed test-copilot-nested-imports-order.md name and nearby fixture layout. Add the main workflow plus the 2–3 nested .md import fragments, and use the harness to verify that the observed marker order is C before B before A.

Written by the indexing model from the issue text.