feat: store packaged user data under data directory

app/gui/__init__.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import os
 import sys
 
+from .. import appconfig
 from . import widgets as _widgets
 from .widgets import *
 
@@ -46,6 +47,17 @@ def main() -> int:
         return 1
     _ensure_offscreen_for_headless_tests()
     app = QApplication.instance() or QApplication(sys.argv)
+    try:
+        appconfig.prepare_data_dir()
+    except appconfig.DataMigrationConflictError as exc:
+        QMessageBox.critical(None, "数据迁移冲突", str(exc))
+        return 1
+    except appconfig.DataDirectoryWriteError as exc:
+        QMessageBox.critical(None, "数据目录不可写", str(exc))
+        return 1
+    except appconfig.ConfigError as exc:
+        QMessageBox.critical(None, "启动配置错误", str(exc))
+        return 1
     window = MainWindow()
     window.show()
     return app.exec()