more features checks. setup improvements

src/Signals/StellaOps.Signals/Scm/Webhooks/GitHubEventMapper.cs

@@ -25,10 +25,18 @@ public sealed class GitHubEventMapper : IScmEventMapper
             _ => (ScmEventType.Unknown, (Func<JsonElement, (ScmEventType, string?, string?)>?)null)
         };
 
-        // Unsupported event types return null
+        // Unsupported event types still return a normalized event with Unknown type
         if (extractor is null)
         {
-            return null;
+            return new NormalizedScmEvent
+            {
+                EventId = deliveryId,
+                Provider = ScmProvider.GitHub,
+                EventType = ScmEventType.Unknown,
+                Timestamp = ExtractTimestamp(payload),
+                Repository = ExtractRepository(payload) ?? new ScmRepository { FullName = "unknown" },
+                Actor = ExtractActor(payload)
+            };
         }
 
         var repository = ExtractRepository(payload);