perf: Add virtual scrolling for stream lists with 100+ entries

[Austinaminu2]

Description

The dashboard and streams page render all stream cards in a flat list. For power users (companies, DAOs) with hundreds of streams, this causes:

• Slow initial render (all DOM nodes created at once)
• High memory usage (all cards in DOM simultaneously)
• Scroll jank on lower-end devices

Current Behavior

fetchStreamsForAddress returns up to 1,000 stream IDs, and the UI renders a card for each. With 500 streams, that's 500+ DOM nodes created on mount.

Proposed Solution

Use a virtualization library like @tanstack/react-virtual or react-window to only render stream cards visible in the viewport (plus a small overscan buffer).

Acceptance Criteria

• Stream lists virtualized — only visible cards are in the DOM
• Smooth scrolling with no visible pop-in or flicker
• Overscan buffer of 3-5 items above and below viewport
• Dynamic row heights supported (stream cards may vary in height)
• Performance improvement measurable: render time < 100ms for 500 streams
• Fallback to flat list for < 50 streams (virtualization overhead not worth it)

[NEA-DEV-coder]

@NEA-DEV-coder has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer, kindly assign me this issue to resolve

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[Bamzy123]

@Bamzy123 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I have experience handling issues like this and I'll submit PR within 2 days max.

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[Emoji-dot]

@Emoji-dot has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would like to work on this issue

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[darcszn]

@darcszn has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi, I'd like to take this on.
I've looked into the issue and have a clear idea of what's causing it.
I'll dig in, write a fix, and make sure it's covered with tests if applicable.
Can I be assigned?

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[drips-wave]

Congratulations, @darcszn! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @darcszn: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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