[FEATURE] Support Cmd+A (Select All) in prompt input field on macOS

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When pressing ⌘+A (Cmd+A) in the prompt input field, the entire terminal screen gets selected instead of just the text in the input field. This makes it impossible to quickly select all text in the prompt for copying or replacing.

This is the macOS equivalent of the issue described in #14789 (Windows/PowerShell).

Proposed Solution

⌘+A should select only the text within the prompt input field, consistent with standard macOS text editing behavior.

Alternative Solutions

Current workarounds:

• Ctrl+U to delete the entire line (but this doesn't help when you want to copy)
• Ctrl+G to open an external editor

These workarounds are not intuitive and add friction to the workflow.

Priority

Medium - Noticeable impact on daily use

Feature Category

CLI commands and flags

Use Case Example

1. Type a long prompt
2. Realize you want to copy it to save or modify elsewhere
3. Press ⌘+A expecting to select the prompt text
4. Instead, the entire terminal history gets selected

Additional Context

Environment:

• Platform: macOS (darwin)
• Issue persists across various terminal emulators

Related issues:

• #14789 - Same request for Windows/PowerShell
• #5005 - Related request for clipboard copy functionality