Enable rendered public API docs QA

[ChrisRackauckas-Claude]

Ignore this PR until reviewed by @ChrisRackauckas.

Summary

• Enables SciMLTesting rendered public API docs coverage for SciPyDiffEq.
• Ignores DiffEqBase-owned reexports for rendered coverage. SciPyDiffEq has no package-owned export, Julia public, or @public declarations on current master.
• Does not add docs, docstrings, [sources], or package path source entries.

Validation

• git diff --check: passed.
• TESTING_GROUP=QA BACKEND_GROUP=CPU /home/crackauc/.juliaup/bin/julia +1.10 --project=. -e "using Pkg; Pkg.instantiate(); Pkg.test(; coverage=false)": passed core tests (odeint_saveat_tests.jl 1/1, scipy_solvers_tests.jl 12/12).
• Direct QA with Julia +1.10: julia --project=test/qa -e "using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate(); include("test/qa/qa.jl")": Quality Assurance | 18 pass | 18 total.
• Runic v1.7.0 --check src test: passed.