feat(ui): repo scan discovers nested repos in subfolders

RepoScanner.Scan now recurses into subdirectories (max depth 5) instead
of only checking the immediate children of the chosen folder. A found
repo (.git as dir or file) is added without descending further; the
selected folder itself is checked too. Skips node_modules/bin/obj/.git/
.vs/packages and reparse points (junctions/symlinks). Per-directory
IOException/UnauthorizedAccessException no longer aborts the whole scan.

src/ClaudeDo.Ui/Services/RepoScanner.cs

@@ -4,23 +4,63 @@ public sealed record RepoCandidate(string Name, string FullPath);
 
 public static class RepoScanner
 {
+    private const int MaxDepth = 5;
+
+    private static readonly HashSet<string> SkipDirNames = new(StringComparer.OrdinalIgnoreCase)
+    {
+        "node_modules", "bin", "obj", ".git", ".vs", "packages",
+    };
+
     public static IReadOnlyList<RepoCandidate> Scan(string parentFolder)
     {
         if (string.IsNullOrWhiteSpace(parentFolder) || !Directory.Exists(parentFolder))
             return Array.Empty<RepoCandidate>();
 
         var result = new List<RepoCandidate>();
-        IEnumerable<string> subdirs;
-        try { subdirs = Directory.EnumerateDirectories(parentFolder); }
-        catch (Exception e) when (e is IOException or UnauthorizedAccessException)
-        { return Array.Empty<RepoCandidate>(); }
-
-        foreach (var dir in subdirs)
-        {
-            var gitPath = Path.Combine(dir, ".git");
-            if (Directory.Exists(gitPath) || File.Exists(gitPath))
-                result.Add(new RepoCandidate(Path.GetFileName(dir), dir));
-        }
+        ScanDirectory(parentFolder, depth: 0, result);
         return result;
     }
+
+    private static void ScanDirectory(string dir, int depth, List<RepoCandidate> result)
+    {
+        if (IsRepo(dir))
+        {
+            result.Add(new RepoCandidate(Path.GetFileName(dir), dir));
+            return;
+        }
+
+        if (depth >= MaxDepth)
+            return;
+
+        IEnumerable<string> subdirs;
+        try { subdirs = Directory.EnumerateDirectories(dir); }
+        catch (Exception e) when (e is IOException or UnauthorizedAccessException)
+        { return; }
+
+        foreach (var subdir in subdirs)
+        {
+            var name = Path.GetFileName(subdir);
+            if (SkipDirNames.Contains(name))
+                continue;
+
+            try
+            {
+                var info = new DirectoryInfo(subdir);
+                if (info.Attributes.HasFlag(FileAttributes.ReparsePoint))
+                    continue;
+            }
+            catch (Exception e) when (e is IOException or UnauthorizedAccessException)
+            { continue; }
+
+            try { ScanDirectory(subdir, depth + 1, result); }
+            catch (Exception e) when (e is IOException or UnauthorizedAccessException)
+            { }
+        }
+    }
+
+    private static bool IsRepo(string dir)
+    {
+        var gitPath = Path.Combine(dir, ".git");
+        return Directory.Exists(gitPath) || File.Exists(gitPath);
+    }
 }