QA: Aqua undefined_exports — `Variable` and `rotate!` leak through `@reexport`

Tracking the @test_broken placeholder for the Aqua undefined_exports sub-check, preserved when converting test/qa/qa.jl to the SciMLTesting run_qa v1.6 form (aqua_broken = (:undefined_exports,)).

Aqua.test_undefined_exports(EasyModelAnalysis) reports two undefined exported names:

• EasyModelAnalysis.Variable — leaks in via @reexport using ModelingToolkit. Variable was historically exported by Symbolics/ModelingToolkit but the binding is no longer defined in the current reexport chain (isdefined(EasyModelAnalysis, :Variable) == false, getproperty throws UndefVarError).
• EasyModelAnalysis.rotate! — name collision: both Plots and LinearAlgebra export rotate!, so the reexported name resolves to nothing usable in EasyModelAnalysis (isdefined(..., :rotate!) == false; load emits WARNING: both Plots and LinearAlgebra export "rotate!"; uses of it ... must be qualified).

Both come transitively through @reexport, not from EasyModelAnalysis's own export list, so they cannot be removed by editing this package's exports without dropping the reexport. The check stays @test_broken until the upstream reexport chain stops re-exporting these dead names (or the package narrows its reexports).

This issue replaces the prior un-tracked broken = true on the hand-rolled Aqua.test_undefined_exports(EasyModelAnalysis, broken = true).

ignore until reviewed by @ChrisRackauckas

Start in test/qa/qa.jl and inspect the SciMLTesting run_qa v1.6 setup, including aqua_broken = (:undefined_exports,). Run Aqua.test_undefined_exports(EasyModelAnalysis) to reproduce the Variable and rotate! reports. Done means the undefined_exports check no longer needs its broken placeholder after the upstream reexport chain or package reexports are corrected.