chore: bump API version to 2026-05-18 and release v4.2.0

Feature type responses now return "usage" instead of "metered".
Consumption model "metered" is unchanged.

Author: decker-dev

build.gradle.kts

@@ -6,7 +6,7 @@ plugins {
 }
 
 group = "co.commet"
-version = "4.1.0"
+version = "4.2.0"
 
 java {
     sourceCompatibility = JavaVersion.VERSION_17

src/main/java/co/commet/CommetHttpClient.java

@@ -29,7 +29,7 @@ public class CommetHttpClient implements AutoCloseable {
 
     private static final String BASE_URL = "https://commet.co";
 
-    public static final String API_VERSION = "2026-05-12";
+    public static final String API_VERSION = "2026-05-18";
 
     private static final int[] RETRYABLE_STATUS_CODES = {408, 429, 500, 502, 503, 504};