feat: add manual saved-location reordering (#712)

[Orinks]

Summary

• preserve saved locations in user-defined order instead of re-sorting them alphabetically in config
• add a manual saved-location sort mode plus a Reorder Saved Locations dialog in the Location menu
• cover the new config and UI behavior with focused regression tests

Testing

• ./.venv/bin/ruff format
• ./.venv/bin/ruff check
• ./.venv/bin/pytest -q tests/test_config_alert_display.py tests/test_config_manager.py tests/test_all_locations_view.py tests/test_settings_dialog_tray_text.py