Fix Unicode encoding issue on Windows stdout

- Add UTF-8 encoding support for stdout output on Windows
- Use sys.stdout.reconfigure() for Python 3.7+ or TextIOWrapper fallback
- Fixes UnicodeEncodeError when outputting special characters to stdout
- Resolves failing Windows CI tests for test_stdout_output_with_special_characters

Author: nikolay-e

src/treemapper/writer.py

@@ -41,8 +41,19 @@ def write_tree_content(f: TextIO) -> None:
                 write_yaml_node(f, child, "  ")
 
     if output_file is None:
-        # Write to stdout
-        write_tree_content(sys.stdout)
+        # Write to stdout with proper UTF-8 encoding
+        # On Windows, sys.stdout might use cp1252 encoding which can't handle Unicode
+        # We need to ensure UTF-8 encoding for proper Unicode support
+        if hasattr(sys.stdout, 'reconfigure'):
+            # Python 3.7+ has reconfigure method
+            sys.stdout.reconfigure(encoding='utf-8')
+            write_tree_content(sys.stdout)
+        else:
+            # Fallback for older Python versions or systems without reconfigure
+            import io
+            utf8_stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')
+            write_tree_content(utf8_stdout)
+            utf8_stdout.flush()
         logging.info("Directory tree written to stdout")
     else:
         # Write to file