🚀 Feature: Expose updateContainerElements method in useFocusTrap

Description

This PR exposes the updateContainerElements method from the underlying focus-trap library, allowing users to dynamically update focus trap containers while the trap is active.

Related Issues

Implements #4848

📋 Changes

• Added updateContainerElements method to UseFocusTrapReturn interface
• Created ContainerElements type alias using Parameters<FocusTrap['updateContainerElements']>[0]
• Updated return type to handle undefined case when trap is not initialized
• Added basic container switching demo in demo.vue

🔧 Technical Details

• Uses TypeScript's Parameters utility type to automatically inherit parameter types from focus-trap library
• Ensures type consistency with the underlying focus-trap library

📚 Example Usage

const { updateContainerElements, activate } = useFocusTrap(target)
activate()
updateContainerElements(target2.value) // Switch to different container

🔄 Breaking Changes

None - this is a purely additive change.