Switch from JuliaFormatter to Runic.jl for code formatting

[ChrisRackauckas-Claude]

Summary

• Updated CI workflow to use fredrikekre/runic-action@v1 instead of JuliaFormatter
• Removed .JuliaFormatter.toml configuration file
• Reformatted all source files with Runic.jl

Changes

This PR migrates the code formatting from JuliaFormatter with SciMLStyle to Runic.jl. Runic.jl is an opinionated formatter (similar to Go's gofmt) that requires no configuration.

Key differences from JuliaFormatter:

• Explicit return statements are added where implicit
• Different indentation and alignment for continuation lines
• Consistent multiline formatting for function arguments

Test plan

• CI format check passes with Runic.jl
• All existing tests still pass

🤖 Generated with Claude Code

[pogudingleb]

I would appreciate waiting until the tests pass at least before merging.

[ChrisRackauckas]

this is an odd case though because it was bound to fail only because of a quirk in the CI system though, because of all of the cache misses that would happen within a 6 hour period, the disk was going to fill which will case all deepsea3/4 CI projects to auto fail

[pogudingleb]

My comment was somewhat independent on the results of CI run. As a general courtesy, I would ask not to merge PRs (especially, AI-assisted) without CI results. Overall, I would prefer to merge the PRs in this repo myself, I am normally relatively efficient with this.

[ChrisRackauckas]

Okay no worries, I'll keep that in mind.