Refactor the shipping rate import process to support bidirectional
data handling (import/export) and implement currency conversion using
system settings. Update the price calculator to ensure valid zone
data is retrieved.
- Update `ShippingRatesImport` to handle both import and export
directions via `SimpleRateSheetImport`.
- Implement AED to IRR conversion during rate importation using
`SystemSetting`.
- Add validation for zone numbers and rate values during import.
- Enhance `PriceCalculatorService` to filter for non-zero zone values.
- Add various debug and testing scripts for pricing and data
structure verification.
