Enh: archiver.py does not identify its messages

The archiver script may be run as part of a .forward file, and most likely all its output is logged to a single file. It would make it easier to trace the cause of errors if they had some context, e.g. a timestamp, possibly other items

Start with archiver.py and inspect how it currently writes output when invoked from a .forward file. Define the message context needed for traceability, such as a timestamp, then verify that errors and other output consistently include that context in the shared log.

Written by the indexing model from the issue text.