🐛(celery) fix metadata task_args order broken by signal sender argument

Restore correct task_args ordering in metadata manager after commit f0939b6f
added sender argument to Celery signals for transcription task scoping,
unexpectedly shifting positional arguments and breaking metadata creation.

Issue went undetected due to missing staging analytics deployment, silently
losing production observability on microservice without blocking transcription
job execution, highlighting need for staging analytics activation.

src/summary/summary/core/analytics.py

@@ -123,7 +123,7 @@ class MetadataManager:
             logger.error("Invalid number of arguments to enable metadata manager.")
             return
 
-        filename, email, _, received_at, *_ = task_args
+        _, filename, email, _, received_at, *_ = task_args
 
         initial_metadata = {
             **initial_metadata,