[Feature] Implement real-time exchange rate feed to replace 20-second polling

[kelly-musk]

Problem

Exchange rates are currently fetched via polling every 20 seconds. For a financial trading interface, 20-second-old rates are stale and the polling creates unnecessary server load.

Fix

Replace polling with a real-time feed:

1. Subscribe to CoinGecko WebSocket stream or a dedicated crypto price provider (Binance, Kraken WebSocket)
2. Push updates to clients via Next.js Server-Sent Events or a Pusher/Ably channel
3. Show live price sparklines in the onramp/offramp calculators

Impact

Medium UX + performance — stale rates and polling overhead.

[NickiM84]

@NickiM84 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello, I'm a fullStack developer with years of experience, I have worked on several projects, can I please work on this.

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[anupam7984]

@anupam7984 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to take this issue and can solve in 1hr. I am full stack web2+web3 developer.

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[Emmanard]

@Emmanard has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

hey kelly i go like work on this one too

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[boseshittu2323-design]

@boseshittu2323-design has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

This issue aligns well with my experience. I have worked extensively on blockchain infrastructure, APIs, UI/UX improvements, and backend services. I can provide a robust and production-ready solution.

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[veemakama]

@veemakama has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer, I would love to work on this. Please assign. Thank you

ℹ️ Repo Maintainers: To accept this application, review their application or assign @veemakama to this issue.