Add SBOM, symbols, traces, and VEX files for CVE-2022-21661 SQLi case

- Created CycloneDX and SPDX SBOM files for both reachable and unreachable images.
- Added symbols.json detailing function entry and sink points in the WordPress code.
- Included runtime traces for function calls in both reachable and unreachable scenarios.
- Developed OpenVEX files indicating vulnerability status and justification for both cases.
- Updated README for evaluator harness to guide integration with scanner output.

src/Signals/StellaOps.Signals/Options/SignalsMongoOptions.cs

@@ -17,10 +17,15 @@ public sealed class SignalsMongoOptions
     /// </summary>
     public string Database { get; set; } = "signals";
 
-    /// <summary>
-    /// Collection name storing normalized callgraphs.
-    /// </summary>
-    public string CallgraphsCollection { get; set; } = "callgraphs";
+    /// <summary>
+    /// Collection name storing normalized callgraphs.
+    /// </summary>
+    public string CallgraphsCollection { get; set; } = "callgraphs";
+
+    /// <summary>
+    /// Collection name storing reachability facts.
+    /// </summary>
+    public string ReachabilityFactsCollection { get; set; } = "reachability_facts";
 
     /// <summary>
     /// Validates the configured values.
@@ -37,9 +42,14 @@ public sealed class SignalsMongoOptions
             throw new InvalidOperationException("Signals Mongo database name must be configured.");
         }
 
-        if (string.IsNullOrWhiteSpace(CallgraphsCollection))
-        {
-            throw new InvalidOperationException("Signals callgraph collection name must be configured.");
-        }
-    }
-}
+        if (string.IsNullOrWhiteSpace(CallgraphsCollection))
+        {
+            throw new InvalidOperationException("Signals callgraph collection name must be configured.");
+        }
+
+        if (string.IsNullOrWhiteSpace(ReachabilityFactsCollection))
+        {
+            throw new InvalidOperationException("Signals reachability fact collection name must be configured.");
+        }
+    }
+}