Task breakdown notes:

• add the GET /entities/items/{item_id}/aliases route to our OpenAPI definition T330892
• Create AliasesInLanguage and Aliases read models. T330895
• implement ItemAliasesRetriever using a TermBuffer (TermBufferAliasesRetriever) T330896
  • create a ItemAliasesRetriever interface with a getAliases( ItemId $itemId ): ?Aliases; method
• use case (GetItemAliases) happy path. T330907
  • create and return response using the data from the ItemAliasesRetriever, and revision metadata
• create a AliasesSerializer (we don't need a dedicated presenter) T330901
• route handler (happy path only) T330902
  • same middlewares as GetItemRouteHandler
  • calls json_encode on the serializer result
  • e2e tests
• validate request and error if item id is invalid (just uses the existing ItemIdValidator but still create a dedicated use case validator) T330898
  • use case + route handler
  • e2e tests
• return appropriate response if the item is a redirect or does not exist. T330908
  • use case + route handler
  • e2e tests
• spec tests T330894
• Use Aliases in ItemData read model. T330909
  • use AliasesSerializer in ItemDataSerializer once done

Looks splendid, thank you!