Ignore extras-only Aqua stale_deps in run_qa

[ChrisRackauckas-Claude]

Please ignore this PR until it has been reviewed by @ChrisRackauckas.

What changed

test/qa/qa.jl now passes Aqua stale_deps ignores for SafeTestsets and SciMLTesting through run_qa's aqua_kwargs. No package version or [compat] change.

Why

Default-branch Downgrade is red while Tests are green (run). run_qa(DiffEqProblemLibrary) runs Aqua against the extras-merged sandbox. SafeTestsets and SciMLTesting live in root [extras] (test harness only) and are flagged as stale deps.

SciMLTesting 2.4–2.9 run_qa does not auto-ignore extras. Aqua's stale_deps = (; ignore = ...) is the supported per-check API. Other Aqua checks are unchanged.

Verification

CI fail-before (Aqua 0.8.16):

Stale dependencies: Test Failed
  Expression: isempty(stale_deps)
  Evaluated: isempty(Base.PkgId[SafeTestsets [...], SciMLTesting [...]])

run_qa forwards aqua_kwargs to Aqua.test_all (SciMLTesting 2.4+).

Not verified here: a live julia-downgrade-compat re-run of the full Core group.

Reviewer note

This is a test-only Aqua ignore for extras that are not package deps. A [compat] bump cannot fix extras-merge stale_deps.