[FEATURE] Add undo support (cmd+z / ctrl+z) in the input prompt

Feature Request

Description

Add standard undo keybinding support in the Claude Code CLI input prompt, similar to how Slack handles text input.

Current Behavior

• Undo shortcuts (cmd+z on macOS, ctrl+z on Windows/Linux) don't work in the input field
• Users cannot undo typed text using keyboard shortcuts

Desired Behavior

• cmd+z (macOS) and ctrl+z (Windows/Linux) should undo typed text in the input prompt
• Should work character-by-character or word-by-word like in Slack and other modern text editors
• Standard redo support (cmd+shift+z / ctrl+shift+z) would also be helpful

Use Case

This would improve the text editing experience when composing messages to Claude, allowing users to quickly undo mistakes without manually deleting text.