fix(receipt): preserve success extra metadata

[EfeDurmaz16]

Summary

• add an extra: keyword to Mpp::Receipt.success
• pass the extra receipt metadata through to the underlying Receipt
• update the Sorbet shim and add a regression test

Why

Mpp::Receipt already models extra, and receipt parsing/formatting preserves it in the Payment-Receipt header. The Receipt.success convenience constructor dropped that metadata, which made it harder for successful payment receipts to carry trace IDs or other opaque settlement evidence without manually constructing the receipt.

Verification

• mise exec ruby@3.4 -- ruby -Ilib -Itest test/mpp/test_parsing.rb -n test_receipt_success_factory_preserves_extra passed after the fix
• mise exec ruby@3.4 -- bundle exec ruby -Itest test/mpp/test_parsing.rb -n test_receipt_success_factory_preserves_extra
• mise exec ruby@3.4 -- bundle exec ruby -Itest test/mpp/test_parsing.rb
• mise exec ruby@3.4 -- bundle exec rake test
• mise exec ruby@3.4 -- bundle exec standardrb
• mise exec ruby@3.4 -- bundle exec srb tc