New payment intent

One record: human checkout URL and machine resource URL.

?Server-side row: label, USDC amount, mint, merchant recipient, status. Public links use an opaque id, not the merchant address in the path.
?Shown on checkout — invoice title, product, or campaign name.
?Decimal USDC. Stored in smallest units (6 decimals) for SPL.
?Wallet that receives the Umbra receiver-claimable UTXO. Must be Umbra-ready to claim.
?https URL — server POSTs JSON intent.settled once after first successful confirm. Leave empty to skip.

Must be http: or https:. Invalid URLs are rejected with 400.

Superteam Frontier · Umbra Side Track

Private pay link plus the same bill for machines as an HTTP 402 resource until Umbra settlement, then 200 with structured content.