fix(core): use exact line matching for duplicate author check

Author: zodiacfireworks

src/edit_python_pe/file_io.py

@@ -34,6 +34,7 @@ def _write_authors_file(
         contents = ""
 
     alias = aliases[0] if aliases else name
-    file_content = f"\n{name}({alias}) <{email}>"
-    if file_content.strip() not in contents:
-        _append_file(file_content, file_path)
+    candidate = f"{name}({alias}) <{email}>"
+    normalized_lines = [line.strip() for line in contents.splitlines()]
+    if candidate not in normalized_lines:
+        _append_file(f"\n{candidate}", file_path)

tests/unit/test_file_io.py

@@ -31,7 +31,7 @@ def test_write_authors_file(self):
             assert email in args[0]
 
         # Case: author already present, should not append
-        existing_line = f"\\n{name}(alias1) <{email}>"
+        existing_line = f"\n{name}(alias1) <{email}>"
         with (
             patch(
                 "edit_python_pe.file_io._read_file", return_value=existing_line