Currency-aware screening and daily usage tracking

SF_SCREEN now supports currency-aware screening in Google Sheets and Excel, and we added daily usage tracking to the website and both add-ins.

• NEW screenCurrency=<code> option for SF_SCREEN(). It defaults to USD and controls monetary filter thresholds, monetary ordering, returned monetary values and the currency labels in the output headers. Currency codes are case-insensitive and minor units such as GBp/GBX are normalized correctly.

• NEW Currency selector in both the Google Sheets and Excel Screener generators. It defaults to USD and omits screenCurrency when USD is selected; choosing another currency adds screenCurrency=<code> to the options argument.

• NEW daily SF usage tracking on the website and in both Google Sheets and Excel, showing real-time tier usage per product.