test(exec): 补 UTF-8 输出解码回归测试（POSIX printf 八进制转义，Java 源码双写反斜杠）

Author: loong10k

src/test/java/io/github/easy4j/opencli/core/OpenCliExecutorFullTest.java

@@ -3,6 +3,7 @@
 import static org.junit.jupiter.api.Assertions.*;
 import io.github.easy4j.opencli.OpenCliExecutionTarget;
 import io.github.easy4j.opencli.OpenCliProperties;
+import java.util.Arrays;
 import org.apache.commons.exec.CommandLine;
 import org.junit.jupiter.api.Test;
 
@@ -31,6 +32,23 @@ void shouldAppendQuotedKeyValueWithTrailingEquals() {
         assertTrue(args[args.length - 1].contains("--key=val"));
     }
 
+    @Test
+    void shouldDecodeUtf8OutputRegardlessOfPlatformCharset() {
+        OpenCliProperties props = new OpenCliProperties();
+        props.setExecutable("/bin/sh");
+        props.setCommandTimeoutMillis(30_000L);
+        OpenCliExecutor executor = new OpenCliExecutor(props);
+
+        // 你 = \344\275\240, 好 = \345\245\275（POSIX printf 八进制转义）。
+        // Java 源码里反斜杠必须双写，否则编译器会把 \344 当成八进制转义吃掉。
+        OpenCliResult result = executor.invoke(Arrays.asList(
+            "-c", "printf '\\344\\275\\240\\345\\245\\275'"));
+
+        assertTrue(result.isSuccess(), "stderr=" + result.getStderr());
+        assertEquals("你好", result.getStdout().trim(),
+            "UTF-8 bytes must decode with explicit UTF-8, not the platform charset");
+    }
+
     @Test
     void shouldConfigureRemoteMode() {
         OpenCliProperties props = new OpenCliProperties();