QA: run_qa v1.6 form + ExplicitImports

[ChrisRackauckas-Claude]

Please ignore until reviewed by @ChrisRackauckas.

Converts test/qa/qa.jl from the hand-rolled Aqua.test_all/JET @test_broken body onto the SciMLTesting 1.6.0 run_qa form, with ExplicitImports enabled.

ExplicitImports findings (explicit_imports = true)

All six checks pass with no ignore-lists and no ei_broken:

• no_implicit_imports ✅
• no_stale_explicit_imports ✅
• all_explicit_imports_via_owners ✅
• all_qualified_accesses_via_owners ✅
• all_qualified_accesses_are_public ✅
• all_explicit_imports_are_public ✅

The src is minimal and already fully-explicit (using RecipesBase: RecipesBase, @recipe, using LinearAlgebra: LinearAlgebra, norm).

The three #50 @test_broken findings — all FIXED (none left broken)

1. Aqua deps_compat — the root Project.toml was missing [compat] entries for the test-only Aqua/JET extras. Added them. (Fix, not suppression.)
2. Aqua piracies — the @recipe-generated RecipesBase.apply_recipe method is owned by DimensionalPlotRecipes; cleared with aqua_kwargs = (; piracies = (; treat_as_own = [apply_recipe])).
3. JET is_key_supported(::Symbol) — that report lives in RecipesBase, not DimensionalPlotRecipes. run_qa's default jet_kwargs = (; target_modules = (pkg,), mode = :typo) scopes it out, so JET.test_package runs green (no jet_broken).

This resolves all of #50.

Deps

• Bump SciMLTesting [compat] floor to "1.6" (root + test/qa).
• Add RecipesBase to the test/qa sub-env (for the apply_recipe reference).
• Drop ExplicitImports from the root [extras]/[targets].test (now transitive via SciMLTesting) and remove the now-redundant Core test/explicit_imports.jl; ExplicitImports runs inside the QA group via run_qa.

Local verification (released SciMLTesting 1.6.0, resolved by Pkg — no dev-from-branch)

Julia 1.10 (lts):  QA/qa.jl | Pass 18  Total 18   (0 broken / 0 fail / 0 error)
Julia 1.11 ("1"):  QA/qa.jl | Pass 18  Total 18   (0 broken / 0 fail / 0 error)
Core (1.10):       Core/recipes.jl green

🤖 Generated with Claude Code