FL-1045 feat: add MappedProductCreated and MappedProductUpdated events
Adds two new EOM events for FL-1014 alcohol-hide feature:
- eom/mappedProductCreated.go: MappedProductCreated struct with Attributes, StoreID, InOrders, CreatedAt, UpdatedAt fields. Pattern follows existing OrderCompleted (GetEventName + Validate via go-playground/validator).
- eom/mappedProductUpdated.go: MappedProductUpdated struct with ID, Attributes, UpdatedAt. UpdatedAt validate:"required" — used by CMS consumer for out-of-order protection.
- topics.go: register EventName/TopicName const pairs and topicMap entries (eom.mapped_product.created / eom.mapped_product.updated).
Tests: 13 new test cases covering JSON roundtrip, validate success/fail for each required field, GetEventName, omitempty for nil Attributes. All 26 tests in eom/ pass.
Closes FL-1045