v5.0.2

• Add CompletionWindowOpenedAsync and CompletionWindowClosedAsync callbacks to PromptCallbacks, invoked when the completion window opens and closes (#293).
• Unicode handling improvements:
  • Handle variant selector 16 (VS16), so the preceding character is measured as a full-width emoji (#292).
  • Handle spacing grapheme extenders U+FF9E–U+FF9F (halfwidth katakana voiced sound marks) (#294).