Replace Jetty WebSocket adapter with JDK HttpClient-based implementation

[Copilot]

Removes the htmlunit-websocket-client (shaded Jetty 9) dependency and replaces it with a java.net.http.WebSocket implementation that ships with the JDK.

New: JdkWebSocketAdapter

• Uses java.net.http.HttpClient + java.net.http.WebSocket (standard since JDK 11)
• Accumulates fragmented text/binary frames before dispatching to WebSocketListener
• Bridges WebClient cookies via a CookieHandler adapter over the existing WebSocketCookieStore
• Supports WebClientOptions.isUseInsecureSSL() via a trust-all SSLContext

Removed

• JettyWebSocketAdapter and the htmlunit-websocket-client Maven dependency
• requires htmlunit.websocket.client from module-info.java (replaced with requires java.net.http)

Housekeeping

• Renamed closeIncommingSession → closeIncomingSession across interface and callers
• Fixed WebSockt typos in Javadoc
• Simplified ArchitectureTest rule now that no production code depends on org.htmlunit.jetty

Backward compatibility

The WebSocketAdapter, WebSocketAdapterFactory, and WebSocketListener interfaces are preserved. Users with custom implementations only need to rename closeIncommingSession → closeIncomingSession.

// Default is now JDK-based — no configuration needed
WebClient client = new WebClient();

// Custom adapter still works via the factory API
client.setWebSocketAdapter(myCustomFactory);

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud