Add agent_id to WebSocket authentication

- Add UUID-based agent_id field to Config struct
- Auto-generate and persist agent_id on first run
- Include agent_id in WebSocket query parameters
- Update production server URL to connect.azcomputerguru.com

Fixes WebSocket connection failure where server expected agent_id parameter.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

agent/src/session/mod.rs

@@ -48,6 +48,7 @@ impl SessionManager {
 
         let transport = WebSocketTransport::connect(
             &self.config.server_url,
+            &self.config.agent_id,
             &self.config.api_key,
         ).await?;