Outsource custom GUI class components to dashgui library

Move reusable GUI primitives (PanelTile, EditablePanelTile, base Tile,
ElevatedPill, SingleLineTextEdit) into the shared dashgui package and
consume them via a file: dependency. EditablePanelTile now accepts an
onError prop so error notification stays app-side.

src/components/article/ArticlePhotoTile.jsx

@@ -2,7 +2,7 @@ import { PureComponent, createRef } from 'react';
 import ContentPasteIcon from '@mui/icons-material/ContentPaste';
 import EditOutlinedIcon from '@mui/icons-material/EditOutlined';
 import { StorageManagerContext } from '../../api/storageManagerContext';
-import { PanelTile } from '../panels';
+import { PanelTile } from 'dashgui/panels';
 import { requireObject } from '../../utils/apiShape';
 import { notifyError } from '../../utils/notify';
 import { prepareArticlePhoto } from '../../utils/prepareArticlePhoto';