Add spell checking configuration

[ChrisRackauckas]

Summary

This PR adds spell checking configuration to maintain code quality.

Changes

.typos.toml Configuration

• Added comprehensive configuration file
• Allows legitimate Julia/scientific terms (e.g., setp, indexin, ists)
• Prevents false positives for domain-specific terminology
• Follows SciML ecosystem standards

SpellCheck.yml Workflow

• Adds GitHub Actions spell checking on pull requests
• Follows SciML standard (matches ModelingToolkit.jl)
• Automatically prevents typos in future contributions

Benefits

• ✅ Automated spell checking on all PRs
• ✅ No false positives for technical terminology
• ✅ Consistent with SciML ecosystem standards
• ✅ Zero maintenance overhead

🤖 Generated by SciML typos standardization