Bump SCCNonlinearSolve compat floor to 1.13 to fix downgrade precompile

[ChrisRackauckas-Claude]

Please ignore until reviewed by @ChrisRackauckas.

Problem

The master downgrade CI lanes — Downgrade / Downgrade Tests - InterfaceI and downgrade-sublibraries / test (lib/ModelingToolkitBase) — resolve SCCNonlinearSolve v1.12.1. That version of iteratively_build_sols preallocates a Vector{NonlinearSolution} and stores a LinearSolution (returned for a linear SCC) directly into it, throwing during the SCCNonlinearProblem precompile workload (src/precompile.jl):

MethodError: Cannot `convert` an object of type
  SciMLBase.LinearSolution{Float64, 1, Vector{Float64}, Vector{Float64}, Nothing, Nothing, Nothing}
to an object of type
  SciMLBase.NonlinearSolution{...}
  [1] setindex!(A::Vector{NonlinearSolution...}, x::LinearSolution..., i1::Int64)
  [2] iteratively_build_sols(alg::SCCNonlinearSolve.SCCAlg{SimpleNewtonRaphson...}, probs::Vector{Any}, ...)
    @ SCCNonlinearSolve .../SCCNonlinearSolve.jl:119

This fails precompilation of ModelingToolkit and its OrdinaryDiffEq extensions on the LTS downgrade run (24 such errors in the InterfaceI lane).

Root cause

The fix for this lives in SCCNonlinearSolve 1.13.0 (commit c5c8120, "fix vector-form SCCNonlinearProblem with linear SCCs"), which routes a linear SCC through a solve_single_scc helper that converts the LinearSolution into a stripped, well-typed NonlinearSolution before storing it. The registered 1.12.1 tree does not contain this helper. The current compat floor SCCNonlinearSolve = "1.8.1" lets the downgrade resolver pick the broken 1.12.1.

Fix

Raise the floor to SCCNonlinearSolve = "1.13" in both Project.toml and lib/ModelingToolkitBase/Project.toml. SCC 1.13s SciMLBase compat (2.153.0 - 3) remains compatible with ModelingToolkitBases SciMLBase = "3.18" floor.

Local verification (Julia 1.10)

Reproduced both directions by pinning the downgrade-resolved versions (SciMLBase 3.18, SimpleNonlinearSolve 2.11.1) and precompiling ModelingToolkit:

• Before (SCC 1.12.1, old floor): PRECOMPILE_FAILED, 2× Cannot convert ... LinearSolution ... NonlinearSolution (same iteratively_build_sols stack as CI).
• After (SCC 1.13.0, new floor): FIX_PRECOMPILE_OK, 0 convert errors, resolves SCCNonlinearSolve v1.13.0.

Scope note

This addresses the SCC 1.12.1 precompile failure that anchors the InterfaceI downgrade lane. The downgrade-sublibraries / ModelingToolkitBase lane also resolves SCC 1.12.1 (first failing package is SCCNonlinearSolveChainRulesCoreExt) but surfaces a separate Module IR does not contain specified entry function cascade that I could not reproduce locally without the full Resolver --min=@alldeps env; this floor bump applies there too and may help, but that lane should be re-checked in CI. The build (Documentation) and Optimization test-group reds are a different root cause — an Optim 2 (NLSolversBase 8) vs NLsolve (NLSolversBase ≤ 7.10, pulled by DiffEqDevTools) resolver deadlock — not addressed here.

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