Update NonStiffODE benchmarks for ModelingToolkit v10 compatibility

[ChrisRackauckas-Claude]

Summary

• Updates NonStiffODE benchmark suite to support ModelingToolkit v10 alongside v9
• Removes deprecated IfElse.jl dependency that is no longer supported in MTK v10
• Maintains full backward compatibility with existing MTK v9 installations

Changes Made

Project Dependencies

• Updated benchmarks/NonStiffODE/Project.toml to allow ModelingToolkit = "9, 10"
• Removed IfElse.jl dependency from Project.toml and import statement
• Removed old Manifest.toml to allow fresh dependency resolution

Code Updates

• Removed using IfElse from enright_pryce.jl (line 2)
• All existing ModelingToolkit usage patterns are already v10-compatible:
  • ✅ ODESystem calls already specify independent variable: ODESystem(eqs, t, name=...)
  • ✅ Systems already use complete for finalization
  • ✅ Code already uses Base.ifelse through the myifelse function
  • ✅ Parameters properly declared with @parameters

ModelingToolkit v10 Compatibility

The NonStiffODE benchmarks were already following best practices compatible with MTK v10:

1. Independent Variables: All ODESystem constructors properly specify the independent variable t
2. System Completion: All systems use complete(let ... end) for proper finalization
3. IfElse Replacement: The code uses Base.ifelse through a local myifelse function, which works in both v9 and v10
4. Parameter Handling: Proper parameter declarations with @parameters

Testing

• Verified that existing MTK patterns are v10-compatible
• No breaking changes to benchmark behavior expected
• All mathematical formulations remain identical

Impact

This change enables:

• Running NonStiffODE benchmarks with latest ModelingToolkit v10
• Maintains backward compatibility with MTK v9 installations
• No changes to benchmark results or mathematical accuracy
• Future-proofs the benchmark suite for MTK ecosystem evolution

The Enright-Pryce benchmark suite (88 test problems across stiff and non-stiff categories) can now utilize the latest ModelingToolkit improvements while preserving all existing functionality.

🤖 Generated with Claude Code