Add the ramps deep link and provider priority design doc

Documents the link format, the ordering rules, the promoCards2 setup blocks
for the info server document, and the partner link instructions.

Author: j0ntz

CHANGELOG.md

@@ -7,6 +7,8 @@
 - added: Exchange-rate cache snapshot in the support log output, plus a `rates-cache-replay` script that re-runs those queries against the rates server and reports the result for each pair.
 - added: "-m" tag on the version number in the Help scene for Maestro test builds
 - added: Sign Message option in the wallet list menu for Bitcoin-family wallets, letting users prove self-hosted wallet ownership to exchanges by signing an exchange-provided message.
+- added: `edge://buy` and `edge://sell` deep links (and their `https://deep.edge.app` equivalents) that open the buy/sell flow, optionally pinning a provider and payment method to the top of the quote options for that visit.
+- added: Provider priority in the buy/sell options for affiliated accounts, configured through the info server promo card data.
 - changed: Sign MoonPay buy/sell widget URLs and bind them to the customer's IP via the info server, for MoonPay's on-ramp IP-matching security upgrade.
 - changed: Style the entire "Already have an account? Sign in" line in the getting-started USP carousel with the tertiary link color, not just "Sign in".
 - changed: Refresh the buy, sell, sort, scan-QR and FIO names icons to the updated design.