test: classify prerequisite lanes and own Avalonia sessions

tests/AcDream.Content.Tests/InstalledSetupCollisionReachabilityTests.cs

@@ -12,6 +12,7 @@ namespace AcDream.Content.Tests;
 /// asserts no such Setup exists, so the deletion cannot remove collision from
 /// any real object.
 /// </summary>
+[Trait("Lane", "InstalledDat")]
 public sealed class InstalledSetupCollisionReachabilityTests
 {
     // Positive controls. These are EXTERNAL constants, measured on 2026-08-06