使用定义的Plain类型代替原始基础类型str，保持代码统一性

astrbot/core/message/components.py

@@ -125,6 +125,8 @@ class Plain(BaseMessageComponent):
     def toDict(self):
         return {"type": "text", "data": {"text": self.text.strip()}}
 
+    async def to_dict(self):
+        return {"type": "text", "data": {"text": self.text}}
 
 class Face(BaseMessageComponent):
     type: ComponentType = "Face"
@@ -610,13 +612,10 @@ class Node(BaseMessageComponent):
                         "data": {"file": f"base64://{bs64}"},
                     }
                 )
-            elif isinstance(comp, str):
-                data_content.append(
-                    {
-                    "type": "text",
-                    "data": {"text": comp.strip()}
-                    }
-                )
+            elif isinstance(comp, Plain):
+                # For Plain segments, we need to handle the plain differently
+                d = await comp.to_dict()
+                data_content.append(d)
             elif isinstance(comp, File):
                 # For File segments, we need to handle the file differently
                 d = await comp.to_dict()