Fix: handle surrogate pairs in FileHistory.store_string

FileHistory.store_string crashes with UnicodeEncodeError when the
input string contains surrogate pairs (e.g., from Windows clipboard
containing emoji). Add errors='replace' to gracefully handle invalid
surrogates by replacing them with the Unicode replacement character.

Fixes #2061

Author: JiajunBernoulli

src/prompt_toolkit/history.py

@@ -300,7 +300,7 @@ def store_string(self, string: str) -> None:
         with open(self.filename, "ab") as f:
 
             def write(t: str) -> None:
-                f.write(t.encode("utf-8"))
+                f.write(t.encode("utf-8", errors="replace"))
 
             write(f"\n# {datetime.datetime.now()}\n")
             for line in string.split("\n"):