add global view state handling

[richard-unterberg]

firestarter: #24

• add zustand
• create map store slice
• implement only viewState

interface ViewState {
    boundingBox: BoundingBox
    center: LatLnLike
    zoom: number
}

• implement in header
• edit examples using new slice

additional resources:

• add simple viewState check: 0ac904d
• https://github.com/richard-unterberg/maplibre-nextjs-ts-starter/blob/main/src/zustand/useMapStore.ts