Extract TransactionsSheetType to unify sheet presentation state

[DRadmir]

No description provided.

[gemini-code-assist]

Code Review

This pull request refactors the sheet presentation logic by introducing a unified TransactionsSheetType enum, which replaces multiple state variables in TransactionsViewModel with a single isPresentingSheet property. This change simplifies the view logic in TransactionsNavigationStack by consolidating sheet modifiers. A review comment suggests further improving the readability of the view body by extracting the sheet's content logic into a separate private @ViewBuilder function.

[gemini-code-assist]

For better readability and maintainability, consider extracting the sheet's content view builder into a separate private @ViewBuilder function. This will make the body of your view cleaner and easier to read, especially since the switch statement contains non-trivial logic for each case.

For example, you could replace the closure with a method reference:

.sheet(item: $model.isPresentingSheet, content: sheetContent)

And then define the sheetContent method within your TransactionsNavigationStack struct:

@ViewBuilder
private func sheetContent(for type: TransactionsSheetType) -> some View {
    switch type {
    case .filter:
        NavigationStack {
            TransactionsFilterScene(model: $model.filterModel)
        }
        .presentationDetentsForCurrentDeviceSize(expandable: true)
        .presentationDragIndicator(.visible)
        .presentationBackground(Colors.grayBackground)
    case .selectAsset(let selectType):
        SelectAssetSceneNavigationStack(
            model: SelectAssetViewModel(
                wallet: model.wallet,
                selectType: selectType,
                searchService: assetSearchService,
                assetsEnabler: assetsEnabler,
                priceAlertService: priceAlertService,
                activityService: activityService
            )
        )
    }
}