Implement Sugiyama

[BjarkeHautop]

Implements Sugiyama layout based on the Rust implementation https://github.com/paddison/rust-sugiyama. Also ports several fixture tests to
verify they give the same output as the source.

The algorithm needs to mutate the graph, so added the needed graph operations to Sugiyama.

Also fixed a bug in the reference implementation: mark_type_1_conflicts
runs before vertex positions are populated there, so its conflict detection is
a no-op, see paddison/rust-sugiyama#26 and paddison/rust-sugiyama#27.

Generated with the help of Claude Code, and manually modified and verified.

Fixes #20

[codecov]

Codecov Report

❌ Patch coverage is 97.51553% with 20 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.47%. Comparing base (6ad1e2f) to head (8159004).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/sugiyama/ordering.jl	92.72%	12 Missing ⚠️
src/sugiyama/coordinates.jl	96.21%	7 Missing ⚠️
src/sugiyama/ranking.jl	99.62%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #100      +/-   ##
==========================================
+ Coverage   97.41%   97.47%   +0.05%     
==========================================
  Files          10       16       +6     
  Lines         580     1385     +805     
==========================================
+ Hits          565     1350     +785     
- Misses         15       35      +20     

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[BjarkeHautop]

Let me know if I can help in any way. I’m mainly interested in getting this algorithm available for one of my packages, so if maintaining it here would be a concern, I’d also be happy to put it in a separate package instead.

[BjarkeHautop]

Made it into a separate package.

[hexaeder]

Hey Bjarke, sorry for not responding here I am super busy with project work currently and havn't had time to review and then plain forgot.
Whats the new package called? Is it still using the NetworkLayout interaface? if so maybe we can just link out to it from the NL.jl docs as an additonal layout.
What I was wondering: Layered layouts normally do not only provide positions for individual nodes but also points along the edges. That doesn't quite fit the interface here, which is why LayeredLayouts.jl exists. Did you solve this in a principled way?

[BjarkeHautop]

No worries!

The package is here https://github.com/BjarkeHautop/Sugiyama.jl - and yes still the same interface.

Initially I just relied on automatic routing via bezier curves if needed (in the downstream package). But I now also exposed the internal dummy nodes routing sugiyama uses, based on how LayeredLayouts does. See https://bjarkehautop.github.io/Sugiyama.jl/dev/05-quick-guide/#Edge-routing-with-CausalStructures