Add WebSocket Gateway for Real-Time Client Updates

[ahmadogo]

The WebSocket gateway has been successfully implemented.

Here's a summary of what was done:

• JWT Authentication: Token validated on handshake (via header, query param, or auth object)
• Room-based Subscriptions: Clients join escrow:{id} rooms for specific escrow updates
• User Notification Channels: Each user auto-joins user:{userId} room
• Reconnection Support: Recent events stored in memory (5 min TTL) for missed event recovery
• CORS Configuration: Enabled for WebSocket connections

Closes #154

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You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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