feat: create currencies with other currencies

[raulriera]

Adds a payment step to the create-currency flow: the launch cost can be paid with USDF or any launchpad currency the user holds.

• Get Started unlocks when any single balance covers the server-driven launch cost, and routes to Add Money otherwise
• New Select Payment Currency step lists balances in USD to match the flow's pricing; under-cost rows are disabled and zero-value balances are hidden
• Ready To Create confirmation before paying; the confirmed row shows an inline loader while the launch submits
• Launchpad payments build the treasury-funded launch transaction the server expects, validating the treasury's spend against the amount the user accepted; the pool's sell fee is absorbed so the user pays exactly the launch cost
• The swap and fee legs are valued at the exact USD components against the pinned reserve proof, and eligibility mirrors the server's acceptance window so a balance displaying $20.00 can always pay
• Purchase and launch analytics now carry the purchased or launched currency alongside the new Payment Mint property; purchase events previously reported only the payment side

Test plan:

• Create a currency paying with USDF
• Create a currency paying with another currency
• Under-cost rows are greyed out and not tappable; picker shows USD values
• Get Started routes to Add Money when no balance can pay
• Purchase and launch events carry Mint and Payment Mint