feat: add PolicyPackSelectorComponent with tests and integration

- Implemented PolicyPackSelectorComponent for selecting policy packs.
- Added unit tests for component behavior, including API success and error handling.
- Introduced monaco-workers type declarations for editor workers.
- Created acceptance tests for guardrails with stubs for AT1–AT10.
- Established SCA Failure Catalogue Fixtures for regression testing.
- Developed plugin determinism harness with stubs for PL1–PL10.
- Added scripts for evidence upload and verification processes.

src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Tests/TaskPackPlannerTests.cs

@@ -36,9 +36,24 @@ public sealed class TaskPackPlannerTests
 
         var resultB = planner.Plan(manifest, inputs);
         Assert.True(resultB.Success);
-        Assert.Equal(plan.Hash, resultB.Plan!.Hash);
-    }
-
+        Assert.Equal(plan.Hash, resultB.Plan!.Hash);
+    }
+
+    [Fact]
+    public void PlanHash_IsPrefixedSha256Digest()
+    {
+        var manifest = TestManifests.Load(TestManifests.Sample);
+        var planner = new TaskPackPlanner();
+
+        var result = planner.Plan(manifest);
+        Assert.True(result.Success);
+        var hash = result.Plan!.Hash;
+        Assert.StartsWith("sha256:", hash, StringComparison.Ordinal);
+        Assert.Equal(71, hash.Length); // "sha256:" + 64 hex characters
+        var hex = hash.Substring("sha256:".Length);
+        Assert.True(hex.All(c => Uri.IsHexDigit(c)), "Hash contains non-hex characters.");
+    }
+
     [Fact]
     public void Plan_WhenConditionEvaluatesFalse_DisablesStep()
     {