AskUserQuestion multiSelect: add select all / unselect all controls

Feature Request

When using AskUserQuestion with multiSelect: true, there's no way for the user to quickly select all or deselect all options. They have to toggle each option individually.

Use Case

I'm building a Claude Code skill (/react-native-ease:refactor) that scans a project for Reanimated/Animated code and offers to migrate components to EaseView. After scanning, it presents a list of migratable components using AskUserQuestion with multiSelect: true.

When there are many components (10+), toggling each one individually is tedious. A "Select All" / "Deselect All" control would make this much more ergonomic.

Current Workaround

I split confirmation into two steps:

1. First ask "Migrate all / Select individually / Abort" (single select)
2. Only show the multi-select picker if user chose "Select individually"

This works but adds an extra step for users who want to exclude just 1-2 components from a large list — they have to go through "Select individually" and then deselect the few they don't want.

Proposed Solution

Add "Select All" and "Deselect All" controls to the multiSelect UI. This could be:

• Buttons/links above the option list
• Keyboard shortcuts (e.g., Ctrl+A to select all)
• A built-in first option that toggles all

Environment

• Claude Code v2.1.74
• macOS