Add price impact warning to swap confirmation

[j0ntz]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes

Dependencies

None

Description

Context

Asana: "Swap - Price Impact Warning" (P1). When users confirm a swap, the effective rate can differ significantly from the market rate due to liquidity depth, spread, and network fees. Without visibility into this, users may unknowingly accept unfavorable rates.

Changes

• Calculate price impact by comparing the fiat value of the quote's from/to amounts against market exchange rates, using biggystring for precision
• Display the price impact percentage inline next to the fiat price in the TO card, color-coded by severity:
  • Grey (deactivatedText): < 5%
  • Orange (warningText): 5–15%
  • Red (dangerText): > 15%
• Show a warning card when price impact exceeds 5%:
  • Price impact only: Dedicated warning about unfavorable market rate
  • Price impact + high fee: Combined card explaining that high network fees contribute to the poor effective rate
  • High fee only: Existing fee warning behavior preserved
• Price impact warning takes precedence over the "Estimated Quote" warning when both apply (since "Estimated Quote" is rendered at the bottom, this prevents showing two warnings, and this warning trumps in severity, anyway)
• Fix pre-existing lint warnings in SwapConfirmationScene and ExchangeQuoteComponent (render function return types, deprecated currencyCode usage)
• Graduate CurrencyRow.tsx from eslint warning-override list

Requirements

If you have made any visual changes to the GUI. Make sure you have:

• Tested on iOS device
• Tested on Android device
• Tested on small-screen device (iPod Touch)
• Tested on large-screen device (tablet)

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1212823425418800