chore(file_operators): use utf-8 as default encoding

app/tool/file_operators.py

@@ -42,17 +42,20 @@ class FileOperator(Protocol):
 class LocalFileOperator(FileOperator):
     """File operations implementation for local filesystem."""
 
+    def __init__(self, encoding: str = "utf-8"):
+        self.encoding = encoding
+
     async def read_file(self, path: PathLike) -> str:
         """Read content from a local file."""
         try:
-            return Path(path).read_text()
+            return Path(path).read_text(encoding=self.encoding)
         except Exception as e:
             raise ToolError(f"Failed to read {path}: {str(e)}") from None
 
     async def write_file(self, path: PathLike, content: str) -> None:
         """Write content to a local file."""
         try:
-            Path(path).write_text(content)
+            Path(path).write_text(content, encoding=self.encoding)
         except Exception as e:
             raise ToolError(f"Failed to write to {path}: {str(e)}") from None