Document exported Catalyst APIs

[ChrisRackauckas-Claude]

This draft PR should be ignored until reviewed by @ChrisRackauckas.

Summary

• Add source-site docstrings for Catalyst-owned exported/public APIs that were missing them.
• Add missing Catalyst API entries to rendered docs pages.
• Enable SciMLTesting rendered public API docs QA with rendered = true, while ignoring dependency-owned reexports for source/rendered API-docs QA instead of documenting those upstream-owned names in Catalyst.
• Remove the added reexports API page and its supporting @autodocs module plumbing.
• Merge current upstream master into the branch without rewriting history.

Verification

• git diff --check passed with no output.
• timeout 3600 ~/.juliaup/bin/julia +1.10 --project=. -e 'using Runic; exit(Runic.main(ARGS))' -- --check --diff $(git diff --name-only origin/master | grep -E '\.(jl|md)$') passed with no output.
• timeout 3600 ~/.juliaup/bin/julia +1.10 --project=test/qa -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate(); include("test/qa/qa.jl")' passed: Quality Assurance | 13 pass, 4 broken, 17 total in 3m30.6s.
• Focused API docs check passed: run_api_docs(Catalyst; rendered=true, ignore=DEPENDENCY_OWNED_PUBLIC_NAMES, rendered_ignore=DEPENDENCY_OWNED_PUBLIC_NAMES) -> Public API documentation | 2 pass, 2 total.
• grep -R "\[sources\]\|path *=\|url *=\|test/Project.toml" -n Project.toml docs/Project.toml test/qa/Project.toml test/Project.toml produced no output.
• Julia 1.10 docs build did not run Documenter because the docs environment is unsatisfiable: SignalDecomposition has no compatible version under the DynamicalSystems v3.6.8, StaticArrays, and Julia 1.10 SparseArrays constraints.
• Julia 1.12 docs build resolved and entered Documenter (SetupBuildDirectory, Doctest: skipped, ExpandTemplates) but exceeded timeout 3600; I terminated the still-CPU-bound Julia process after the timeout wrapper had elapsed over one hour.

No full Pkg.test() run was attempted; this PR is scoped to docs/docstrings/rendered QA.

[ChrisRackauckas-Claude]

Updated the QA SciMLTesting compat bound to 2.2 in test/qa/Project.toml.

Local verification:

• git diff --check -> passed with no output.
• timeout 3600 env GROUP=QA /home/crackauc/.juliaup/bin/julia +release --startup-file=no --project=. -e 'using Pkg; Pkg.test()' -> passed. Observed summary: Quality Assurance | 12 pass, 7 broken, 19 total; final line: Testing Catalyst tests passed.

Commit: 296134e2.

Runic was not run because this patch only changes a TOML compat entry, not Julia source.

[ChrisRackauckas-Claude]

Updated the branch to restore the QA compat floor to SciMLTesting = "2.1" in test/qa/Project.toml.

Local validation:

• git diff --check passed.
• GROUP=QA timeout 3600 /home/crackauc/.juliaup/bin/julia +release --startup-file=no --project=. -e 'using Pkg; Pkg.test()' passed: Quality Assurance | 12 pass / 7 broken / 19 total.
• Exact floor smoke forced SciMLTesting v2.1.0 after resolver downgrade v2.2.0 => v2.1.0 and passed: Quality Assurance | 12 pass / 7 broken / 19 total.