Function build_maker_fill_report 

pub fn build_maker_fill_report(
    mo: &PolymarketMakerOrder,
    trade_id: &str,
    trader_side: PolymarketLiquiditySide,
    trade_side: PolymarketOrderSide,
    taker_asset_id: &str,
    account_id: AccountId,
    instrument_id: InstrumentId,
    price_precision: u8,
    size_precision: u8,
    currency: Currency,
    liquidity_side: LiquiditySide,
    ts_event: UnixNanos,
    ts_init: UnixNanos,
) -> FillReport

Builds a [FillReport] from a PolymarketMakerOrder and trade-level context.

Used by both the WS stream handler and REST fill report generation since both share the same PolymarketMakerOrder type for maker fills. Maker fills never pay commission per Polymarket’s fee rules.