Refactor code structure and optimize performance across multiple modules

src/Policy/__Tests/StellaOps.Policy.Tests/SplCanonicalizerTests.cs

@@ -1,11 +1,13 @@
 using StellaOps.Policy;
 using Xunit;
 
+using StellaOps.TestKit;
 namespace StellaOps.Policy.Tests;
 
 public class SplCanonicalizerTests
 {
-    [Fact]
+    [Trait("Category", TestCategories.Unit)]
+        [Fact]
     public void Canonicalize_SortsStatementsActionsAndConditions()
     {
         const string input = """
@@ -54,7 +56,8 @@ public class SplCanonicalizerTests
         Assert.Equal(expected, canonical);
     }
 
-    [Fact]
+    [Trait("Category", TestCategories.Unit)]
+        [Fact]
     public void ComputeDigest_IgnoresOrderingNoise()
     {
         const string versionA = """
@@ -71,7 +74,8 @@ public class SplCanonicalizerTests
         Assert.Equal(hashA, hashB);
     }
 
-    [Fact]
+    [Trait("Category", TestCategories.Unit)]
+        [Fact]
     public void ComputeDigest_DetectsContentChange()
     {
         const string baseDoc = """