- Move card tab selector to a left sidebar (CardList) with pagination
- Replace separate side toggle and layer panels with EditorTabs
- Move copy code button from layer panel to DeckHeader
- Simplify PropertiesEditorPanel by removing front/back toggle and
using a select for shape
Introduce a deck registry to track all active deck instances. This
allows users to select and merge multiple decks with matching
dimensions into a single print preview and export session.