Fix GraphQL Content-Currency validation against the store named by the Store header (#41242) - #41247

Description (*)

A GraphQL request that sends Store: <store code> together with Content-Currency: <code> is rejected with Please correct the target currency whenever that currency is allowed only on the requested website and not on the default one.

Root cause: Magento\GraphQlCache\Controller\Plugin\GraphQl::beforeDispatch() runs validateRequest() before processHeaders(). Magento\DirectoryGraphQl\Controller\HttpRequestValidator\CurrencyValidator therefore checks the header against storeManager->getStore(), which is still the default store, because the Store header is only applied by StoreProcessor inside processHeaders(). The validator throws, processHeaders() is skipped, and the second validation pass in GraphQl::dispatch() fails the same way. This ordering was introduced by AC-821 for #31336 (store validation must run before the store is switched) and tightened by AC-11729, so the plugin order is not changed here.

The fix makes CurrencyValidator resolve the store it validates against from the Store header itself, falling back to the current store when the header is absent. An unknown or inactive store code keeps producing Requested store is not found, matching StoreValidator, so the validator no longer depends on the order in which the two validators are registered.

Tests:

• New unit test Magento\DirectoryGraphQl\Test\Unit\Controller\HttpRequestValidator\CurrencyValidatorTest covering the header/no-header paths, rejected currencies, unknown and inactive store codes, empty header and normalisation.
• New API-functional test Magento\GraphQl\Directory\CurrencyHeaderValidationTest with a second website whose only allowed, base and default currency is NOK (absent from the default scope): Store + Content-Currency: NOK succeeds, Content-Currency: NOK without Store is rejected, Store + Content-Currency: USD is rejected.

Related Pull Requests

None.

Fixed Issues (if relevant)

1. Fixes GraphQl Content-Currency exception when default config differs from website/storeview. #41242
2. Same defect as reported in Error "Please correct the target currency" when switching store with different currency than default one on GraphQl #38732

Manual testing scenarios (*)

1. Create a second website, store and store view (code nok_sv).
2. Set catalog/price/scope to Website. For the new website set currency/options/allow, currency/options/base and currency/options/default to NOK. Leave the default scope on USD.
3. POST /graphql with headers Store: nok_sv, Content-Currency: NOK and query { storeConfig { store_code base_currency_code } }.
4. Before the fix: Please correct the target currency. After the fix: store_code is nok_sv, base_currency_code is NOK.
5. Repeat without the Store header: still rejected, because NOK is not allowed on the default store.

Questions or comments

Local gates: unit, integration (no integration tests changed), PHPCS, PHPStan and the Static Tests reproduction were run on the changed files; the API-functional test relies on the upstream WebAPI build.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined templates (if applicable)
• All automated tests passed successfully (all builds are green)