QA: run_qa v1.6 form + ExplicitImports

Replace the hand-rolled Aqua + ExplicitImports QA files (qa_tests.jl,
explicit_imports_tests.jl) with a single qa.jl on the SciMLTesting 1.6
`run_qa` form, with ExplicitImports enabled (all six checks).

- Aqua: `run_qa` runs the full `Aqua.test_all` (11 checks); no broken
  markers or aqua_kwargs tweaks needed — all pass.
- ExplicitImports: `explicit_imports = true`. Two checks needed ignore
  lists for third-party symbolic-stack internal names re-exported but not
  owned/public by ModelingToolkit/Symbolics (documented per source pkg);
  the other four checks pass unmodified.
- JET: `jet = false` in run_qa. Whole-package JET hits a toplevel
  `invalid redefinition of constant ModelOrderReduction.TSVD` (the exported
  `TSVD` struct collides with the `TSVD` dependency package under JET's
  toplevel virtualizer). The existing targeted `report_call` checks in
  jet_tests.jl provide the JET coverage and stay as a separate group file.

test/qa/Project.toml: drop ExplicitImports (transitive via SciMLTesting),
keep Aqua (ambiguities child-proc needs it direct) and JET (jet_tests.jl),
bump SciMLTesting compat to "1.6".

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas

test/qa/Project.toml

@@ -1,6 +1,5 @@
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
-ExplicitImports = "7d51a73a-1435-4ff3-83d9-f097790105c7"
 JET = "c3a54625-cd67-489e-a8e7-0a5a0ff4e31b"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 ModelOrderReduction = "207801d6-6cee-43a9-ad0c-f0c64933efa0"
@@ -10,11 +9,10 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
 Aqua = "0.8"
-ExplicitImports = "1"
 JET = "0.9, 0.10, 0.11"
 LinearAlgebra = "1"
 SafeTestsets = "0.0.1, 0.1"
-SciMLTesting = "1"
+SciMLTesting = "1.6"
 Test = "1"
 
 [sources]

test/qa/explicit_imports_tests.jl

@@ -0,0 +1,39 @@
+using SciMLTesting, ModelOrderReduction, Test
+
+run_qa(
+    ModelOrderReduction;
+    explicit_imports = true,
+    # Whole-package JET (`report_package`/`test_package`) hits a toplevel
+    # `invalid redefinition of constant ModelOrderReduction.TSVD` error: the package
+    # exports a `TSVD` struct whose name collides with the `TSVD` dependency package
+    # under JET's toplevel virtualizer. JET coverage is provided by the targeted
+    # `report_call` checks in jet_tests.jl, which sidestep the toplevel re-eval.
+    jet = false,
+    ei_kwargs = (;
+        # Internal symbolic-stack names that ModelingToolkit/Symbolics re-export but
+        # neither own nor mark public. `via_owners` flags the re-export; `are_public`
+        # flags the non-public status. ModelOrderReduction uses them as internal API.
+        all_qualified_accesses_via_owners = (;
+            ignore = (
+                # owner ModelingToolkitBase, accessed via ModelingToolkit
+                :get_eqs, :get_initial_conditions, :get_iv, :get_observed,
+                :get_unknowns, :get_var_to_name, :topsort_equations,
+                # owner SymbolicUtils, accessed via Symbolics
+                :scalarize, :unwrap,
+                # owner SymbolicIndexingInterface, accessed via Symbolics
+                :getname,
+            ),
+        ),
+        all_qualified_accesses_are_public = (;
+            ignore = (
+                # not public in ModelingToolkit
+                :get_eqs, :get_initial_conditions, :get_iv, :get_observed,
+                :get_unknowns, :get_var_to_name, :topsort_equations,
+                # not public in Symbolics
+                :getname, :scalarize, :unwrap, :rhss, :value,
+                # not public in SymbolicUtils
+                :isadd, :ismul,
+            ),
+        ),
+    )
+)