Additional billing emails and editable billing address

The Payment Methods page has been extended so accounting and finance teams can be CC’d on every invoice.

• A new “Additional billing emails” component lets you add or remove multiple recipients who receive invoice PDFs alongside the primary owner.
• Each email entry is validated and saved independently — removing one doesn’t disturb the rest.
• The billing address can now be edited inline; previously it required contacting support.
• The payment-methods loader was hardened against partial responses so the page always renders, even if the address service is slow.

Existing billing email recipients carry over automatically and no further action is required.