feat: romaji plugin (without dict)

RomajiConverter.Core/Options/ToRomajiAIOptions.cs

@@ -0,0 +1,16 @@
+namespace RomajiConverter.Core.Options
+{
+    public class ToRomajiAIOptions : ToRomajiOptions
+    {
+        public string BaseUrl { get; set; }
+
+        public string Model { get; set; }
+
+        public string ApiKey { get; set; }
+
+        /// <summary>
+        /// 提示词，可以不传，使用默认提示词
+        /// </summary>
+        public string Prompt { get; set; }
+    }
+}