Websocket communication

### **Description**

Replace the current **TCP polling mechanism** with **WebSocket communication** in `wazuh-agent-status`.
The goal is to establish a persistent connection between the client and server so that the client receives **real-time agent status updates** without polling.

Key tasks:

* Add WebSocket server support in the background process (`server` binary).
* Update client to subscribe to server via WebSocket.

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### **Definition of Ready**

* [x] Codebase is cloned and dependencies resolved.
* [x] Current TCP polling implementation is understood.

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### **Acceptance Criteria**

* [x] Client establishes persistent WebSocket connection to server.
* [ ] Server broadcasts agent status changes to all connected clients.
* [x] Client updates tray icon / CLI immediately upon receiving status update.

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### **Definition of Done**

* [x] WebSocket server implemented in `server` binary.
* [x] Client binary consumes WebSocket messages instead of polling.
* [x] Unit and integration tests created for WebSocket communication.
* [ ] Documentation updated (README, developer guide) with new WebSocket design and configuration (`--use-websocket` flag).
* [ ] Manual test verified: stopping/starting Wazuh agent triggers immediate tray client update without polling.

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