qa: enforce strict SciMLTesting 2.4 checks

[ChrisRackauckas-Claude]

Ignore until reviewed by @ChrisRackauckas.

Summary

• require SciMLTesting 2.4 and use plain run_qa(ModelingToolkitStandardLibrary) without QA or documentation exceptions
• replace package-owned non-public qualified accesses and resolve symbolic dispatch ambiguities exposed by strict QA
• place connector docstrings on their original definitions and render public Blocks/domain API references
• enable strict documentation checks, doctests, link checking, and clean docs builds
• repair two analysis-point test operating points required by current ModelingToolkit initialization behavior

Validation

• Pkg.test()
• strict run_qa(ModelingToolkitStandardLibrary)
• strict Documenter build with doctests, cross-reference checks, rendering, and link checking
• Runic.main(["--check", "src", "test", "docs"])
• git diff --check

The clean-main package test failure in test/test_analysis_points.jl was independently reproduced before correcting the missing loop-opening operating points.