Replace duplicated table/list markup in the Kunde list page and Manifest
list with the shared dashgui RecordList component, and document dashgui/lists
in the README.
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.
Add number & setting API endpoints, StorageManager caches, and a Settings
dialog (tabs for settings keys and number ranges) reachable from the user
menu. Show Kundennummer and creation date in the Kunde list, and refactor
Neuer Kunde to show an auto-generated number with group select.
Placeholder sub-pages are dropped from routing and nav until delivery/return flows exist; the new-customer group dropdown now matches the API sort order.
