feat: add script tts backend

backend-single/src/main/java/com/emotion/service/TtsEngineClient.java

@@ -0,0 +1,36 @@
+package com.emotion.service;
+
+public interface TtsEngineClient {
+
+    TtsEngineResult synthesize(String text, String voice, String outputPath);
+
+    class TtsEngineResult {
+        private final boolean success;
+        private final String audioPath;
+        private final Long durationMs;
+        private final String errorMessage;
+
+        public TtsEngineResult(boolean success, String audioPath, Long durationMs, String errorMessage) {
+            this.success = success;
+            this.audioPath = audioPath;
+            this.durationMs = durationMs;
+            this.errorMessage = errorMessage;
+        }
+
+        public boolean isSuccess() {
+            return success;
+        }
+
+        public String getAudioPath() {
+            return audioPath;
+        }
+
+        public Long getDurationMs() {
+            return durationMs;
+        }
+
+        public String getErrorMessage() {
+            return errorMessage;
+        }
+    }
+}