Raise FIRK/MIRK downgrade compat floors

[ChrisRackauckas-Claude]

Ignore this PR until reviewed by @ChrisRackauckas.

Summary

• Raise SciMLBase compat in BoundaryValueDiffEqFIRK and BoundaryValueDiffEqMIRK from 3 to 3.30 so the sublibraries match the in-tree BoundaryValueDiffEqCore floor.
• Allow LinearSolve 4.2 in the same sublibraries; after the SciMLBase floor is fixed, the downgrade resolver can otherwise hit an empty intersection with LinearSolve v4.2.1.
• This is only the downgrade resolver-floor fix. The separate MIRK Dual runtime failure is handled in Fix MIRK extrema boundary conditions under AD #542, and Shooting is handled in Fix MultipleShooting caches for tagged AD states #541.

Evidence

• Current master downgrade logs fail at resolution because the downgrade action pins SciMLBase v3.0.0 while the path dependency BoundaryValueDiffEqCore requires SciMLBase >= 3.30.
• Local reproduction after only the SciMLBase floor exposed the next resolver conflict: LinearSolve@4.2.1 was incompatible with LinearSolve = "2.36.2, 3".
• After this patch, local downgraded FIRK Pkg.test(...; force_latest_compatible_version=false, allow_reresolve=false) instantiated with SciMLBase v3.35.1 and LinearSolve v4.2.1, so the resolver failure is gone.
• After this patch, local downgraded MIRK Pkg.test(...; force_latest_compatible_version=false, allow_reresolve=false) also got past resolution and reached the known MIRK Dual runtime failures fixed separately in Fix MIRK extrema boundary conditions under AD #542.

Local verification

• git diff --check passed.
• FIRK downgraded Pkg.test with Julia 1.10 and BOUNDARYVALUEDIFFEQ_TEST_GROUP=Core no longer failed at resolution. It completed FIRK Expanded Basic Tests | 234 pass, 20 broken, 254 total in 81m17.4s, then timed out after 2 hours in test/nested/firk_basic_tests.jl without an Error During Test marker before termination. I am not claiming the full FIRK downgraded package test passes locally.
• MIRK downgraded Pkg.test with Julia 1.10 no longer failed at resolution. It reported the expected Float64(::ForwardDiff.Dual) failures in mirk.jl:338 (Swirling Flow III, big-defect interpolant, max/min solution), which are covered by Fix MIRK extrema boundary conditions under AD #542, then timed out after 1 hour. I am not claiming MIRK passes locally from this PR alone.

[github-actions]

Benchmark Results (Julia v1.11)

Time benchmarks

	master	e7b6a52...	master / e7b6a52...
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK2()	0.569 ± 0.017 s	0.532 ± 0.0059 s	1.07 ± 0.034
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK3()	11.8 ± 0.49 ms	11.4 ± 0.98 ms	1.04 ± 0.099
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK4()	2.56 ± 0.16 ms	2.5 ± 0.33 ms	1.02 ± 0.15
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK5()	2.96 ± 0.13 ms	2.9 ± 0.12 ms	1.02 ± 0.06
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK6()	1.46 ± 0.063 ms	1.47 ± 0.19 ms	0.996 ± 0.13
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = false)	1.5 ± 0.083 ms	1.55 ± 0.11 ms	0.971 ± 0.088
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = true)	3.91 ± 1.2 ms	3.32 ± 0.72 ms	1.18 ± 0.44
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.0371 ± 0.0025 s	0.0405 ± 0.0062 s	0.915 ± 0.15
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.0618 ± 0.0057 s	0.0626 ± 0.013 s	0.987 ± 0.23
Simple Pendulum/IIP/Shooting(Tsit5())	0.162 ± 0.08 ms	0.176 ± 0.083 ms	0.922 ± 0.63
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK2()	0.695 ± 0.019 s	0.788 ± 0.028 s	0.882 ± 0.039
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK3()	16.5 ± 4.7 ms	16.5 ± 6.7 ms	1 ± 0.5
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK4()	2.93 ± 0.17 ms	3.35 ± 0.53 ms	0.874 ± 0.15
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK5()	3.66 ± 0.34 ms	3.71 ± 0.5 ms	0.986 ± 0.16
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK6()	1.78 ± 0.21 ms	1.82 ± 0.4 ms	0.974 ± 0.24
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = false)	3.51 ± 1.9 ms	3.1 ± 0.86 ms	1.13 ± 0.68
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = true)	6.84 ± 6.4 ms	6.95 ± 7.1 ms	0.984 ± 1.4
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.0868 ± 0.0098 s	0.0935 ± 0.011 s	0.929 ± 0.15
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.146 ± 0.018 s	0.143 ± 0.013 s	1.02 ± 0.16
Simple Pendulum/OOP/Shooting(Tsit5())	0.586 ± 0.078 ms	0.576 ± 0.17 ms	1.02 ± 0.33
time_to_load	7.76 ± 0.24 s	7.43 ± 0.24 s	1.05 ± 0.047

Memory benchmarks

	master	e7b6a52...	master / e7b6a52...
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK2()	0.389 M allocs: 0.0443 GB	0.389 M allocs: 0.0443 GB	1
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK3()	0.0436 M allocs: 4.88 MB	0.0436 M allocs: 4.88 MB	1
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK4()	15.7 k allocs: 1.65 MB	15.7 k allocs: 1.65 MB	1
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK5()	22.1 k allocs: 2.03 MB	22.1 k allocs: 2.03 MB	1
Simple Pendulum/IIP/BoundaryValueDiffEqMIRK.MIRK6()	12.8 k allocs: 1.05 MB	12.8 k allocs: 1.05 MB	1
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = false)	25.5 k allocs: 1.82 MB	25.5 k allocs: 1.82 MB	1
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = true)	0.049 M allocs: 3.39 MB	0.049 M allocs: 3.39 MB	1
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.553 M allocs: 0.0535 GB	0.553 M allocs: 0.0535 GB	1
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.833 M allocs: 0.0778 GB	0.833 M allocs: 0.0778 GB	1
Simple Pendulum/IIP/Shooting(Tsit5())	4.63 k allocs: 0.224 MB	4.63 k allocs: 0.224 MB	1
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK2()	0.89 M allocs: 0.984 GB	0.89 M allocs: 0.984 GB	1
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK3()	0.0932 M allocs: 24.8 MB	0.0932 M allocs: 24.8 MB	1
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK4()	0.0324 M allocs: 3.96 MB	0.0324 M allocs: 3.96 MB	1
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK5()	0.045 M allocs: 4.99 MB	0.045 M allocs: 4.99 MB	1
Simple Pendulum/OOP/BoundaryValueDiffEqMIRK.MIRK6()	25.3 k allocs: 2.17 MB	25.3 k allocs: 2.17 MB	1
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = false)	0.142 M allocs: 10.2 MB	0.142 M allocs: 10.2 MB	1
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = true)	0.266 M allocs: 18.7 MB	0.266 M allocs: 18.7 MB	1
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = false)	2.52 M allocs: 0.279 GB	2.52 M allocs: 0.279 GB	1
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = true)	3.82 M allocs: 0.404 GB	3.82 M allocs: 0.404 GB	1
Simple Pendulum/OOP/Shooting(Tsit5())	0.0373 M allocs: 1.69 MB	0.0373 M allocs: 1.69 MB	1
time_to_load	0.161 k allocs: 11.4 kB	0.161 k allocs: 11.4 kB	1