Workspace repo discovery follows directory symlinks: a symlink loop lists the same repo dozens of times, and repo fetch then runs that many concurrent fetches into it #232

What's wrong

DiscoverGitReposRecursive (KtsuTools.Repo/RepoService.cs:1144-1168) recurses into every entry Directory.GetDirectories returns. That includes directory symlinks and junctions (reparse points). It never skips them and never de-duplicates by real path, so:

• A symlink that points at a repo, or at a directory above one, lists that repo again under a second path.
• A symlink that points back up the tree (tools/loop -> ..) is followed repeatedly until the OS symlink-depth limit throws. Every level on the way adds the same repos again.

The callers include TryDiscoverWorkspaceRepos (line ~700, used by ktools git and repo lfs install), PullAllAsync (~507), FetchAllAsync and WalkAndCacheAsync. SaveCacheAsync de-duplicates by path string only, so every alias reaches the cache as a separate repo.

Reproduction

Take a workspace with ws/A/.git and ws/tools/loop -> ... A copy of the function returns 41 entries, every one of them repo A, reached as ws/tools/loop/A, ws/tools/loop/tools/loop/A, and so on.

With that workspace:

• ktools git status prints A 41 times.
• repo pull runs git pull --autostash in A 41 times.
• repo fetch is parallel by default, so it runs 41 concurrent fetches into the same repository. They contend for ref locks, and the ones that lose report failures.

Suggested fix

• Skip reparse points while walking. For example, use Directory.EnumerateDirectories(directory, "*", new EnumerationOptions { AttributesToSkip = FileAttributes.ReparsePoint, IgnoreInaccessible = true }), or check new DirectoryInfo(subDir).LinkTarget is not null before recursing.
• Optionally also de-duplicate the result by fully resolved path. That still lets a workspace root which is itself a symlink work; see sync copies files into repos reached through a symlinked path but never lists or commits them (macOS /tmp, /var affected) #188 for that case.

Acceptance criteria

• A test with a symlinked subdirectory that loops back to the workspace root returns each repo exactly once and does not throw.
• A test with a symlink pointing directly at a repo returns that repo once.

Related but distinct: #230 (the AllDirectories scans stopping on an unreadable directory) and #188 (a symlinked workspace root in sync).