NocoDB returns records keyed by field titles, but the code was looking
up values by field IDs, always getting None. This caused every update
to overwrite existing seeders instead of appending.
Hardcode "Id" and "Seeding Users" field names as class constants and
remove the --id-field and --seeding-field CLI args.
update_record was using the custom field ID to identify rows in PATCH
requests instead of NocoDB's internal Id primary key. This prevented
proper row matching, causing values to be overwritten instead of
appended to the comma-separated seeder list.
