v2.2.2: dummy release for auto-update test

- Show app version in window title for visual confirmation after update
- No functional changes — purely a test bump to verify the
  single-file (main.exe alone) auto-update flow end-to-end.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/version.py

@@ -4,4 +4,4 @@
 릴리스 시 이 값을 올린 후 git tag → push.
 CHANGELOG.md의 최상단 항목과 일치시킬 것.
 """
-__version__ = '2.2.1'
+__version__ = '2.2.2'