test(fleet): use shared runtime contract helpers

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Summary

• Pins reusable workflows to aio-fleet main commit ce6221a.
• Replaces duplicated container-contract test logic with the shared aio_fleet.testing helper surface.

What changed

• Updated generated caller workflows to the next-wave aio-fleet SHA.
• Kept repo-specific runtime facts in a small local test matrix.

Why

• Moves repeated AIO test policy into aio-fleet while keeping app/template-specific facts local.

Validation

• .venv/bin/python scripts/validate-template.py --all
• bash scripts/validate-derived-repo.sh .
• .venv/bin/python -m pytest tests/template
• trunk check --show-existing --all --no-fix --no-progress --color=false
• Fleet validate --all and sync-workflows --dry-run from aio-fleet