CBL-7550 : Added shutdown for executor and okhttp (#93)

* CBL-7550 : Added shutdown for executor and okhttp

* Added API Doc for shutdown

* Updated the API Doc

* Update the PostShutdown API Doc

Author: Aniket392

java/lib/src/main/java/com/couchbase/lite/CouchbaseLite.java

@@ -78,4 +78,25 @@ public static void init(boolean debug) {
     public static void init(boolean debug, @NonNull File rootDir, @NonNull File scratchDir) {
         CouchbaseLiteInternal.init(debug, rootDir, scratchDir);
     }
+
+    /**
+     * Shuts down Couchbase Lite's shared executors.
+     * Call when shutting down your application/container to allow clean JVM exit.
+     *
+     * <p>
+     * This method releases shared executors used by Couchbase Lite.
+     * It should be called when the host application or container is shutting down
+     * to allow the process to terminate cleanly without being blocked by
+     * active executors.
+     * </p>
+     *
+     * <p>
+     * After this call, internal shared executors are stopped and no longer perform work.
+     * Couchbase Lite should not be used again until the process restarts.
+     * </p>
+     *
+     */
+    public static void shutdown() {
+        CouchbaseLiteInternal.shutdown();
+    }
 }