Add unit tests for RancherHubConnector and various exporters

- Implemented tests for RancherHubConnector to validate fetching documents, handling errors, and managing state.
- Added tests for CsafExporter to ensure deterministic serialization of CSAF documents.
- Created tests for CycloneDX exporters and reconciler to verify correct handling of VEX claims and output structure.
- Developed OpenVEX exporter tests to confirm the generation of canonical OpenVEX documents and statement merging logic.
- Introduced Rust file caching and license scanning functionality, including a cache key structure and hash computation.
- Added sample Cargo.toml and LICENSE files for testing Rust license scanning functionality.

src/Excititor/StellaOps.Excititor.WebService/Endpoints/MirrorEndpoints.cs

@@ -292,28 +292,30 @@ internal static class MirrorEndpoints
         return export is not null;
     }
 
-    private static string ResolveContentType(VexExportFormat format)
-        => format switch
-        {
-            VexExportFormat.Json => "application/json",
-            VexExportFormat.JsonLines => "application/jsonl",
-            VexExportFormat.OpenVex => "application/json",
-            VexExportFormat.Csaf => "application/json",
-            _ => "application/octet-stream",
-        };
+    private static string ResolveContentType(VexExportFormat format)
+        => format switch
+        {
+            VexExportFormat.Json => "application/json",
+            VexExportFormat.JsonLines => "application/jsonl",
+            VexExportFormat.OpenVex => "application/json",
+            VexExportFormat.Csaf => "application/json",
+            VexExportFormat.CycloneDx => "application/json",
+            _ => "application/octet-stream",
+        };
 
     private static string BuildDownloadFileName(string domainId, string exportKey, VexExportFormat format)
     {
         var builder = new StringBuilder(domainId.Length + exportKey.Length + 8);
         builder.Append(domainId).Append('-').Append(exportKey);
-        builder.Append(format switch
-        {
-            VexExportFormat.Json => ".json",
-            VexExportFormat.JsonLines => ".jsonl",
-            VexExportFormat.OpenVex => ".openvex.json",
-            VexExportFormat.Csaf => ".csaf.json",
-            _ => ".bin",
-        });
+        builder.Append(format switch
+        {
+            VexExportFormat.Json => ".json",
+            VexExportFormat.JsonLines => ".jsonl",
+            VexExportFormat.OpenVex => ".openvex.json",
+            VexExportFormat.Csaf => ".csaf.json",
+            VexExportFormat.CycloneDx => ".cyclonedx.json",
+            _ => ".bin",
+        });
         return builder.ToString();
     }