修改分区功能

bms-back/sql/price/README_billing_postcode.md

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+# Billing quote / order sync: postcode -> zone
+
+## Rule
+- Whether a country needs a zone is decided by `bms_product_country` (rows with `zone_code`).
+- If the product+country has zones: request **must** include `destPostcode`.
+- Zone is resolved at runtime: `destPostcode` -> `prc_zone_detail` + `prc_zone` -> `zone_code`, then match `bms_product_country`.
+- Billing tables store **postcode only**, not zone columns:
+  - `prc_quote.dest_postcode`
+  - `prc_order_bill.dest_postcode` (already existed)
+
+## SQL
+Run: `bms-back/sql/price/billing_postcode_alter.sql`
+
+## API fields
+- Request: `destPostcode` on `/api/tms/price/quote` and `/api/tms/price/bill` (and console `/price/billing/quote`).
+- Response may include `zoneId` / `zoneCode` / `zoneName` for display only (not persisted on bill/quote tables).
+
+## Errors (i18n)
+- `price.quote.postcodeRequired`
+- `price.quote.postcodeZoneNotFound`
+- `price.quote.zonePriceNotHit`
+- `price.quote.priceNotHit`