Feature: Add PopConfirm component

It would be useful to have a PopConfirm component for lightweight confirmation interactions.

PopConfirm is commonly used when an action needs confirmation but does not require a full AlertDialog or modal dialog. For example, confirming destructive actions such as deleting an item.

A typical usage could look like:

[ Delete ]

        ┌──────────────────────────┐
        │  Are you sure?            │
        │                           │
        │  [Cancel] [Confirm]       │
        └──────────────────────────┘

Proposed API

The API could be similar to other component libraries:

PopConfirm::new()
    .title("Are you sure you want to delete this item?")
    .description("This action cannot be undone.")
    .confirm_text("Delete")
    .cancel_text("Cancel")
    .on_confirm(...)
    .child(Button::new("delete").label("Delete"))

The exact API can follow the existing Popover and button patterns in gpui-kit.

Why

Currently, developers need to compose Popover and other components themselves to implement this common interaction pattern.

Having a built-in PopConfirm would provide:

• A consistent confirmation UX across applications
• A reusable pattern for destructive or potentially irreversible actions
• Less repetitive application-level code
• Consistent positioning, styling, focus handling, and dismissal behavior

Relationship to AlertDialog

This component would complement AlertDialog rather than replace it:

• PopConfirm: lightweight, contextual confirmation anchored to the triggering element
• AlertDialog: more prominent modal confirmation for important decisions

A PopConfirm could potentially be implemented on top of the existing Popover component.