Modify ingest_source to add coordinates to Positions table

once Positions table is in the template, modify ingest_source to optionally add coords to Positions table (in addition to Sources table).

Related issue https://github.com/astrodbtoolkit/astrodb-template-db/issues/174

Start by reading ingest_source and the related issue #174, then confirm how the template defines the Positions and Sources tables. Determine how optional coordinates should be handled for Positions without changing existing Sources behavior. Done means ingest_source can add coordinates to Positions when provided and continues to work when they are absent.

Written by the indexing model from the issue text.