feat: Add RustFS artifact object store and migration tool

- Implemented RustFsArtifactObjectStore for managing artifacts in RustFS.
- Added unit tests for RustFsArtifactObjectStore functionality.
- Created a RustFS migrator tool to transfer objects from S3 to RustFS.
- Introduced policy preview and report models for API integration.
- Added fixtures and tests for policy preview and report functionality.
- Included necessary metadata and scripts for cache_pkg package.

bench/Scanner.Analyzers/StellaOps.Bench.ScannerAnalyzers.Tests/BenchmarkScenarioReportTests.cs

@@ -0,0 +1,58 @@
+using StellaOps.Bench.ScannerAnalyzers;
+using StellaOps.Bench.ScannerAnalyzers.Baseline;
+using StellaOps.Bench.ScannerAnalyzers.Reporting;
+using Xunit;
+
+namespace StellaOps.Bench.ScannerAnalyzers.Tests;
+
+public sealed class BenchmarkScenarioReportTests
+{
+    [Fact]
+    public void RegressionRatio_ComputedWhenBaselinePresent()
+    {
+        var result = new ScenarioResult(
+            "scenario",
+            "Scenario",
+            SampleCount: 5,
+            MeanMs: 10,
+            P95Ms: 12,
+            MaxMs: 20,
+            Iterations: 5,
+            ThresholdMs: 5000);
+
+        var baseline = new BaselineEntry(
+            "scenario",
+            Iterations: 5,
+            SampleCount: 5,
+            MeanMs: 8,
+            P95Ms: 11,
+            MaxMs: 15);
+
+        var report = new BenchmarkScenarioReport(result, baseline, regressionLimit: 1.2);
+
+        Assert.True(report.MaxRegressionRatio.HasValue);
+        Assert.Equal(20d / 15d, report.MaxRegressionRatio.Value, 6);
+        Assert.True(report.RegressionBreached);
+        Assert.Contains("+33.3%", report.BuildRegressionFailureMessage());
+    }
+
+    [Fact]
+    public void RegressionRatio_NullWhenBaselineMissing()
+    {
+        var result = new ScenarioResult(
+            "scenario",
+            "Scenario",
+            SampleCount: 5,
+            MeanMs: 10,
+            P95Ms: 12,
+            MaxMs: 20,
+            Iterations: 5,
+            ThresholdMs: 5000);
+
+        var report = new BenchmarkScenarioReport(result, baseline: null, regressionLimit: 1.2);
+
+        Assert.Null(report.MaxRegressionRatio);
+        Assert.False(report.RegressionBreached);
+        Assert.Null(report.BuildRegressionFailureMessage());
+    }
+}