fix: memory leak in message store using cap and virtualization

[deepak0x]

This PR fixes a critical memory leak where the message store could grow without bounds in high-volume channels, eventually leading to application crashes due to out-of-memory errors.

The issue is resolved using a two-part approach:

• Memory capping to limit how many messages are stored in state.
• Virtualized rendering to efficiently display messages without DOM or memory overhead.

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Closes #1092

Problem

• The message store kept accumulating messages in active channels.
• High-traffic rooms could grow the store indefinitely.
• This caused excessive memory usage and eventual application crashes (OOM).

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Solution

• Enforce a strict upper bound on the number of messages kept in memory.
• Render messages using virtualization so only visible items exist in the DOM.
• Delegate scroll and pagination logic to the virtualization layer.

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Changes Made

1. Message Store (packages/react/src/store/messageStore.js)

• Enforced a hard cap of 500 messages in both setMessages and upsertMessage.
• Added strict chronological sorting by timestamp to maintain correct message order.
• Logic now always keeps the newest 500 messages and drops the oldest when the limit is exceeded.

2. Virtualized Rendering (packages/react/src/views/MessageList/MessageList.js)

• Replaced direct .map() rendering with react-virtuoso.
• Only visible messages are rendered in the DOM, greatly reducing memory and render cost.
• Configured with alignToBottom to preserve standard chat behavior.

3. Scroll Management (packages/react/src/views/ChatBody/ChatBody.js)

• Refactored ChatBody to delegate scroll handling to Virtuoso.
• Removed manual scroll listeners and calculations.
• Connected loadMoreMessages to Virtuoso’s startReached callback to support seamless history loading up to the capped limit.