Barrier Trials Copy
Copies tblbarriertrials from the source database into
trial_meeting, trial_race, and trial_run
in the destination. Uses the Excel field mapping file to drive column mappings.
Foreign keys (course, runner, jockey, trainer, country) are resolved from existing
config_id_mappings — no duplicate records are created.
Truncates trial_meeting, trial_race, trial_run and removes config_id_mappings. Use before a full re-run.