Rework add/remove lists view: present create-list locally and move create button into list

[Dimillian]

Motivation

• The current add/remove list flow uses a global sheet for creating lists which dismisses the current flow and interrupts toggling a user into a newly created list.
• The create-list action in the navigation toolbar is not discoverable in the context of adding/removing a user from lists.
• Creating a list should be presented locally so the user can immediately continue toggling the target account into the newly created list.

Description

• Added a top Section with a Button labeled Label("account.list.create", systemImage: "plus") inside ListAddAccountView so the create action appears in the list content.
• Introduced @State private var isPresentingCreateList and present ListCreateView() with .sheet(isPresented:) to show the create flow locally on top of the current sheet.
• Removed reliance on the global RouterPath create action and the toolbar create button while keeping the Done action in the toolbar.
• Modified file Packages/Lists/Sources/Lists/AddAccounts/ListAddAccountView.swift to implement the above UX and presentation changes.

Testing

• Attempted to build the app with xcodebuild -scheme IceCubesApp -project IceCubesApp.xcodeproj -destination 'platform=iOS Simulator,name=iPhone 15' build, but xcodebuild is not available in the environment so the build could not be executed.
• No other automated tests were run in this environment due to the missing build tooling.
• Manual inspection of the changed ListAddAccountView UI code confirms the create button is now in-list and ListCreateView is presented locally via .sheet.
• Further verification should include running the app locally and executing the project tests with xcodebuild or in Xcode to confirm compile and runtime behavior.

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Codex Task