QA: Aqua/JET findings marked @test_broken pending fix

While converting the test suite to the grouped-tests CI layout, the QA group surfaced two genuine findings (one Aqua, one JET) that are currently marked @test_broken so the QA group stays green and the grouped-tests PR can merge. They should be fixed and un-broken.

Finding 1 — Aqua deps_compat (check_deps)

Aqua.test_all "Compat bounds" -> deps check fails: the package depends on SparseArrays (2f01184e-e22b-5df5-ae63-d93ebab69eaf) but the main Project.toml [compat] section has no compat entry for it. Aqua error:

FiniteVolumeMethod1D deps: result is non-empty -> SparseArrays [2f01184e-...] has no compat entry

Fix: add a SparseArrays compat bound (e.g. SparseArrays = "1") to [compat].

Finding 2 — JET report_package (4 possible errors)

JET.test_package(FiniteVolumeMethod1D; target_defined_modules=true) reports 4 possible errors:

• Dirichlet{F,P}(; f, p) kwarg constructor (src/boundary_conditions.jl:25): no matching method (::Type{Dirichlet{_A,_B}})(::Any, ::Any).
• Neumann{F,P}(; f, p) kwarg constructor (src/boundary_conditions.jl:57): no matching method (::Type{Neumann{_A,_B}})(::Any, ::Any).
• init(prob::FVMProblem, alg; kwargs...) (src/solve.jl:66): no matching method init(::ODEProblem{...}, ::Any).
• init(prob::FVMProblem, alg; kwargs...) (src/solve.jl:66): no matching kwcall for that init.

All other Aqua sub-checks pass. To keep QA running every other check, the QA driver now calls Aqua.test_all(FiniteVolumeMethod1D; deps_compat=false) plus a @test_broken for the deps finding, and replaces the failing JET.test_package with a @test_broken placeholder. These should be fixed and un-broken.

Ignore until reviewed by @ChrisRackauckas.

Start with the QA driver, Project.toml, src/boundary_conditions.jl, and src/solve.jl, then run the Aqua and JET checks described in the issue. Trace the two keyword constructors and init calls, and verify that the dependency compatibility check passes. Done means the reported findings are fixed, the @test_broken placeholders are removed, and the full QA group remains green.