[Dev/Debug Aid] Add logging to syncDetails

Since syncdetails does some complex checks, it would be useful to have some logging of the basis on which a certain sync details response was sent in order to debug issues.

Start by locating the syncDetails entry point in the Avni server and tracing the complex checks that determine each response. Identify the decision basis that would help debug issues, then verify that the resulting logs explain the response without exposing inappropriate data; the issue names no files or tests to run.

Written by the indexing model from the issue text.