Make Iranian Rial (IRR) the sole base currency for shipping rates:
- RateImportService now converts all imported rates to IRR at import
time using the current daily exchange rate (source currency AED/USD/
EUR/IRR). Rates are stored in rate_entries with currency='IRR'.
- PriceCalculatorService looks up IRR rates directly — no conversion
at calc time. Also fixes a pre-existing bug where extras (in IRR)
were incorrectly added to the AED base before conversion.
- RateEntry::lookup() default currency changed from 'AED' to 'IRR'.
- Migration changes the column default to 'IRR'.
- Filament import form: relabel 'Rate currency' to 'Source currency
(in Excel file)' with helper text explaining the conversion.
- WordPress JS: update price summary labels from 'درهم' to 'ریال'
and drop the deprecated net_dirham field.
Architectural benefit: rates are 'frozen' in IRR at import time —
daily exchange rate changes only affect NEW imports, not already-
stored rates. This is more stable and predictable for customers.
58493feca4