Feature Request: Quick Access to Keyboard Shortcuts via `?`

[LyalinDotCom]

What would you like to be added?

Problem

New users often struggle to discover the powerful keyboard shortcuts available in the CLI (e.g., toggling modes, file selection, history search). While /help exists, it requires sending a command and takes the user away from their current context. Users need a faster, context-sensitive way to see available shortcuts without losing their place.

Proposed Solution

Implement a "Quick Shortcuts Help" panel that appears inline when the user types ? at the start of an empty prompt.

Behavior

• Trigger: Typing ? when the input buffer is empty.
• Display: Renders a concise list of key shortcuts above the prompt.
• Dismissal:
  • Pressing ? again: Closes the panel and inserts ? into the prompt.
  • Pressing Escape: Closes the panel.
  • Pressing Backspace: Closes the panel.
  • Typing any other character: Closes the panel and handles the input normally (e.g., inserts the character).

UI Layout

• Header: "Shortcuts (for more, see /help)"
• Grid:
  • Wide Terminals: 3-column layout.
  • Narrow Terminals: 1-column layout (responsive).
• Content:
  • ! : shell mode
  • Shift+Tab : cycle mode
  • Ctrl+V : paste images
  • @ : select file or folder
  • Ctrl+Y : YOLO mode
  • Ctrl+R : reverse-search history
  • Esc Esc : clear prompt / rewind
  • Alt+M (or Option+M on macOS) : raw markdown mode
  • Ctrl+X : open external editor

Update

This is now resolved by: #18035