QA: Aqua/JET findings marked @test_broken pending fix

The grouped-tests QA group surfaced the following genuine Aqua/JET findings. They are currently wrapped as @test_broken in test/qa/qa.jl so the QA group runs green in CI; they should be fixed and un-broken.

Aqua (Aqua.test_all) — Aqua.test_all(...; ambiguities=false, unbound_args=false, undefined_exports=false, deps_compat=false) is used so the remaining Aqua sub-checks (project_extras, stale_deps, piracies, persistent_tasks) still run; the following are @test_broken:

• ambiguities: method ambiguities found.
• unbound_args: unbound type parameters found.
• undefined_exports: undefined exports found.
• deps_compat: missing [compat] entries (deps + extras).

JET (JET.test_package)

• 1 possible error found: setfield!: immutable struct of type LabelledArrays.LArray cannot be changed: setfield!(x::LArray, :__x, y::Any) in setproperty!(x::LArray, s::Symbol, y::Any) (src/larray.jl:96). The JET.test_package assertion is @test_broken.

All passing Aqua sub-checks remain enforced. These checks should be fixed and the @test_broken markers removed.

Ignore until reviewed by @ChrisRackauckas.

Start in test/qa/qa.jl, where the Aqua.test_all and JET.test_package checks are marked @test_broken. Inspect the reported immutable-field failure at src/larray.jl:96 and review each listed Aqua finding. Done means the findings are fixed, the @test_broken markers are removed, and the grouped QA checks pass.