rzv CLI 0.13.0: billing commands

rzv 0.13.0 adds billing invoices, automatic recharge, billing country, credit pack checkout and the billing portal.

• rzv billing invoicesLists the invoices for the selected workspace.
• rzv billing auto-rechargeReads and sets automatic recharge. Turning it on needs a person signed in, not an API key.
• rzv billing countryReads and sets the billing country for the selected workspace.
• rzv billing checkout --pack --operation-idPrints a link to the payment page for a credit pack, where card payments are available for your workspace. Card payments stay off until Runzivo turns them on; until then, buy credits by bank transfer from the portal. Reuse --operation-id when you retry the same purchase.
• rzv billing portalPrints a link to the billing portal.
• A refused billing change says why: your role does not allow it, or you need to run rzv login again.
• Downloads are on GitHub at https://github.com/Runzivo/rzv-cli/releases/latest. Release notes are on the same page.