Function persist_fill_with_side_effects_in_tx 

pub fn persist_fill_with_side_effects_in_tx(
    conn: &mut PgConnection,
    fill: &Fill,
    side_effects: &FillSideEffect,
) -> Result<(bool, bool)>

Persist a fill (trade + taker/maker fill rows) and apply ledger side effects in the caller’s transaction.

Returns (taker_inserted, maker_inserted) booleans – false means the row already existed (idempotent ON CONFLICT DO NOTHING).