QA fails after SciMLTesting 2.1 migration on rendered docs and reexports

Clean main currently fails its QA group independently of downgrade testing.

Reproduction:

GROUP=QA julia +1.10 --project=. -e 'using Pkg; Pkg.test()'\n```\n\nAt clean `main` `4e718b866ee7f671ef0b4e154aae1d15f54abfa2`, the run exits 1 with 17 passed / 2 failed / 1 broken. The failures are:\n\n- `LinearizationOpPoint` and `set_defaults` are public but not rendered in the docs.\n- 1,129 public reexports are not approved by QA.\n\nEquivalent before/after validation identifies `6624ad4` (PR #306, “Update SciMLTesting QA compat to 2.1”) as the introducing change: the preceding `7f541f5` QA setup resolves SciMLTesting 1.8 and passes 16 / 1 broken (exit 0), while `6624ad4` adds `api_docs_kwargs.rendered = true` and enables the stricter public-doc/reexport checks.\n\nThis is the same QA signature seen in PR #313; #313 only changes NLopt test compatibility and its downgrade job passes. Existing issue #300 concerns undefined exports and is distinct.

Start with GROUP=QA julia +1.10 --project=. -e 'using Pkg; Pkg.test()' and compare the QA behavior before and after commit 6624ad4. Inspect the api_docs_kwargs.rendered setting and the public-documentation and reexport checks. Done means the QA group passes on clean main, including the rendered LinearizationOpPoint and set_defaults entries and approved reexports.