fix: move inbox attribute addition outside static pipeline cache

The static cache was storing inbox attributes alongside handler
attributes, causing cross-contamination between pipeline builders
with different inbox configurations. Now the cache only stores the
handler's declared attributes, and inbox attributes are applied fresh
each time based on the current _inboxConfiguration.

This fixes both the original observability test failures (leaked inbox
attributes) and the default inbox publish test (inbox added twice on
cache miss).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: holytshirt

src/Paramore.Brighter/PipelineBuilder.cs

@@ -208,12 +208,11 @@ private IHandleRequests<TRequest> BuildPipeline(RequestHandler<TRequest> implici
                         .Where(attribute => attribute.Timing == HandlerTiming.Before)
                         .OrderByDescending(attribute => attribute.Step);
 
-                AddGlobalInboxAttributes(ref preAttributes, implicitHandler);
-
                 s_preAttributesMemento.TryAdd(implicitHandler.Name.ToString(), preAttributes);
-
             }
 
+            AddGlobalInboxAttributes(ref preAttributes, implicitHandler);
+
             var firstInPipeline = PushOntoPipeline(preAttributes, implicitHandler, requestContext, instanceScope);
 
 
@@ -250,12 +249,11 @@ private IHandleRequestsAsync<TRequest> BuildAsyncPipeline(RequestHandlerAsync<TR
                         .Where(attribute => attribute.Timing == HandlerTiming.Before)
                         .OrderByDescending(attribute => attribute.Step);
 
-                AddGlobalInboxAttributesAsync(ref preAttributes, implicitHandler);
-
                 s_preAttributesMemento.TryAdd(implicitHandler.Name.ToString(), preAttributes);
-
             }
 
+            AddGlobalInboxAttributesAsync(ref preAttributes, implicitHandler);
+
             var firstInPipeline = PushOntoAsyncPipeline(preAttributes, implicitHandler, requestContext, instanceScope, continueOnCapturedContext);
 
             if (!s_postAttributesMemento.TryGetValue(implicitHandler.Name.ToString(), out IOrderedEnumerable<RequestHandlerAttribute>? postAttributes))