fix(appserver): preserve turn completion status

Author: loong10k

src/main/java/io/github/easy4j/codex/appserver/CodexAppServerTurn.java

@@ -344,11 +344,19 @@ private void onTurnCompleted(JsonNode params) {
                 .threadId(threadId)
                 .turnId(turnId)
                 .content(finalContent)
-                .finishReason("stop")
+                .finishReason(extractFinishReason(params))
                 .build());
         close();
     }
 
+    private String extractFinishReason(JsonNode params) {
+        String status = firstText(params.path("turn"), "status");
+        if (!hasText(status)) {
+            status = firstText(params, "status", "reason");
+        }
+        return hasText(status) ? status : "completed";
+    }
+
     private CompletableFuture<JsonNode> newRpc(String method, Map<String, Object> params) {
         long id = rpcIds.incrementAndGet();
         Map<String, Object> payload = new LinkedHashMap<>();