feat: add Java 26 HTTP/3 HttpClient demo with explanation

Signed-off-by: https://github.com/Someshdiwan <someshdiwan369@gmail.com>

Author: Someshdiwan

Java-Versions/Java 26/src/Http3ClientDemo.java

@@ -0,0 +1,85 @@
+import java.net.URI;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+
+public class Http3ClientDemo {
+    public static void main(String[] args) {
+        try {
+            var client = HttpClient.newBuilder()
+                .version(HttpClient.Version.HTTP_3) // Enable HTTP/3
+                .build();
+
+            var request = HttpRequest.newBuilder()
+                .uri(new URI("https://www.google.com")) // Any HTTPS site
+                .GET()
+                .build();
+
+            var response = client.send(request, HttpResponse.BodyHandlers.ofString());
+
+            System.out.println("Status Code: " + response.statusCode());
+            System.out.println("Response (first 200 chars):");
+            System.out.println(response.body().substring(0, 200));
+
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}
+
+/*
+What changed: Previous vs New
+
+Previous Java style:
+- HttpClient used HTTP/1.1 or HTTP/2
+- No native HTTP/3 support
+- Developers depended on external libraries for HTTP/3
+
+New Java 26 style:
+- Built-in HTTP/3 support in HttpClient
+- Just set version(HttpClient.Version.HTTP_3)
+- Cleaner and native implementation
+
+Old approach example idea:
+var client = HttpClient.newBuilder()
+        .version(HttpClient.Version.HTTP_2)
+        .build();
+
+Why the new approach is better:
+- Faster communication (uses QUIC protocol)
+- Reduced latency
+- Better performance on unstable networks
+- No need for external libraries
+
+Pros:
+1. Better performance
+   - Faster than HTTP/2 in many cases
+
+2. Reduced latency
+   - Faster connection setup
+
+3. Built-in support
+   - No third-party dependency required
+
+4. Modern networking
+   - Uses QUIC (UDP-based)
+
+Cons:
+1. Server dependency
+   - Only works if server supports HTTP/3
+
+2. Fallback behavior
+   - May fall back to HTTP/2 automatically
+
+3. Debugging complexity
+   - Harder to debug compared to HTTP/1.1
+
+Best use case:
+- High-performance web applications
+- APIs with low-latency requirements
+- Mobile or unstable network environments
+
+Compile and run:
+javac Http3ClientDemo.java
+java Http3ClientDemo
+*/