Render ConvergenceTrajectory in package docs

[ChrisRackauckas-Claude]

Please ignore this PR until reviewed by @ChrisRackauckas.

What changed and why

Add the exported ConvergenceTrajectory type to DiffEqDevTools' package-local rendered API page. The root OrdinaryDiffEq docs already rendered its docstring, but DiffEqDevTools QA deliberately checks lib/DiffEqDevTools/docs/src; the type was therefore public and documented yet still failed the package's rendered-doc assertion.

An independent bisect identified 528f821 as the first bad commit. That change introduced and exported the type but added it only to the root docs tree.

Failing before / passing after

Before this entry:

Public API documentation: Test Failed
unrendered = [:ConvergenceTrajectory]

With this patch, the focused check passes:

Test Summary:             | Pass  Total  Time
Public API documentation  |    2      2  0.3s

Local verification

• The exact SciMLTesting.run_api_docs package check: 2/2 passed after failing on the unfixed docs tree.
• julia +1.12 --startup-file=no --project=docs docs/make.jl: completed successfully and rendered the full documentation site.
• Runic --check --docstrings, typos, and git diff --check: passed.

The complete package QA group still encounters the independent Aqua persistent-task failure present on master. A proposed version-only workaround was tested with fresh before/after cache controls, failed identically, and was closed at #4311. This PR fixes the rendered-doc assertion only. GPU, downstream, and prerelease-Julia groups were not run because this changes documentation only.

[ChrisRackauckas-Claude]

CI triage: all completed failures are the two independently reproduced master Downstream issues. ProbNumDiffEq’s Julia 1.10 resolver failure is addressed by #4320. PositiveIntegrators’ LinearSolve 5 compatibility failure is addressed upstream by NumericalMathematics/PositiveIntegrators.jl#216. No completed red check currently points to this PR’s changed behavior.