fix: use cp1252 encoding for config.cfg (Windows umlauts)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

migrate.py

@@ -31,7 +31,7 @@ def parse_color(value):
 def migrate(config_path="config.cfg"):
     """Import old config.cfg into the SQLite database."""
     config = ConfigParser()
-    config.read(config_path, encoding="utf-8")
+    config.read(config_path, encoding="cp1252")
 
     init_db()
     conn = get_db()