feat: add connection state recovery and flexible auth

[RobinPcrd]

Connection State Recovery Support

Implements Socket.IO v4.6.0 connection state recovery for the Java client.

What's New

Connection State Recovery

• Client tracks session offset and PID across reconnections
• Check recovery status with socket.isRecovered()
• Get current offset with socket.getLastOffset()

Flexible Auth (Breaking Change)

• Changed auth from Map<String, String> to JSONObject
• Now supports complex auth payloads

// Before
opts.auth = Map.of("token", "abc123");

// After  
JSONObject auth = new JSONObject();
auth.put("token", "abc123");
opts.auth = auth;

Testing

• All tests updated for Socket.IO v4.8.1
• Added recovery scenario test
• Fixed namespace event issues

Works with Socket.IO v4.6+ servers that have connection state recovery enabled.