Simplify LinkSafeFileSystem Enumerate and fix alias-of-link shadowing

[ionite34]

Stacked on #1743 (NeuralFault's fix for diffusion_models shadowing DiffusionModels).

SM creates Models/diffusion_models -> Models/DiffusionModels for every SwarmUI install, and the walk claimed folders in reversed push order, so on NTFS the alias won and the real folder got skipped. Every diffusion model ended up indexed under the alias as Unknown.

The diagnosis in #1743 is right, this reworks the implementation to be simpler and more robust, closing one more bug case.

Why shaped like this

We can't just use Directory.EnumerateFiles(..., AllDirectories). That's what the indexer did before #1385, and .NET's recursion follows links, so a link back up the tree loops forever. If we follow links, the walk has to remember where it's been. That part doesn't go away.

#1743 split "where it's been" into three maps with two different comparers, and the regression @mohnjiles caught came from that: one branch forgot to check one of the maps. With one set there's nothing to forget.

The other half is deciding who owns a folder when two paths reach it. "Real folders before links" fixes the Swarm case, but it's one case short. Say a user moves DiffusionModels to another drive and links it back, and Swarm's alias then points at that link. Both are links now, so "real first" has nothing to prefer, and whichever sorts first wins. diffusion_models happens to sort after on NTFS, but a_alias doesn't, and on Linux sibling order is effectively random. Same bug, one level up.

So the rule is: walk paths in order of how many links they go through, and the first walk to reach a folder owns it. Real folders are just the zero-link case.

What changed

• EnumerateFiles is a recursive Walk with one HashSet and a PriorityQueue of links, keyed by how many links each path goes through.
• GetRealPath follows one link at a time and counts as it goes. That also stops it resolving through subst drives, which listed every file twice when the root was on a subst letter (Windows, there since Send Current SM Workflow to Current ComfyUI Instance - To More Easily Visualize #1385).
• Dedup skips log at Debug, since the Swarm alias trips one on every index.

Tests

Funny thing: before this, you could follow links inline with no queue at all and every test still passed, because every alias in the suite sorted after DiffusionModels. So the new a_alias rows are the ones that matter. We broke each rule on purpose to make sure something catches it:

Broken on purpose	Caught by
Follow links inline, no queue	RealFolderShadowedByLink("a_alias"), alias-of-link ("a_alias")
Plain FIFO instead of link count	alias-of-link ("a_alias")
Ordinal comparer	junction case mismatch, root spelled in different case
returnFinalTarget: true	alias-of-link ("a_alias")

Also new: dangling link, root spelled in a different case, link to an ancestor of the root, link inside a link target, two links looping into each other.

LinkSafeFileSystemTests is 28/28 on Windows. We haven't run it on Linux or macOS yet, how relative symlinks resolve there is read from .NET's source.

What it doesn't cover

If you hand-make a link that stores its target through a different drive alias (T:\... while the root is reached via C:\...), files can still show up twice. SM's own links are always spelled from ModelsDirectory, so they can't hit this. Fixing it properly means comparing folders by file ID instead of path text, which felt like its own PR.

🐺 Generated with Lykos (Opus 5.5, Reviewed by Fable 5.1)

The merge-base changed after approval.