fix(react-bindings): getSnapshot caching

[oliverlaz]

💡 Overview

Fixes #2006. Cold-derived Observable instances (remoteParticipants$ and similar) get read twice in strict mode, and as such, the derivative runs multiple times, creating multiple shallow-equal arrays.
Although this isn't exactly an issue, as we had this behavior before #1953, the emitter warning could be confusing.

Docs: https://github.com/GetStream/docs-content/pull/778

[Copilot]

Pull Request Overview

This PR addresses an issue where cold-derived Observable instances (like remoteParticipants$) are read multiple times in React strict mode, causing redundant derivations and emitter warnings. The fix introduces a ref-based caching mechanism for getSnapshot to ensure the initial value is only read once.

Key changes:

• Introduced valueRef and initialRenderRef to cache observable values and prevent multiple reads during strict mode
• Moved value retrieval logic from getSnapshot into initialization and subscription callbacks
• Simplified the getSnapshot function to return cached values from refs

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