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.
- Remove 'Artikel angelegt.' snackbar from NewArticleTile
- Remove 'Kategorie angelegt.' snackbar from NewCategoryTile
- Remove dead handleEnableAllCategories method and binding from CompanySettingsDialog