[Feature Request] Add Ctrl+L keyboard shortcut for clearing terminal output

Feature Request

Problem

Currently, users need to type the clear command to clear the Claude Code terminal output. This is less convenient than the standard Ctrl+L shortcut that works in most terminals and CLI applications.

Proposed Solution

Add support for Ctrl+L (Control+L) keyboard shortcut to clear the terminal output, similar to how it works in bash, zsh, and other terminal applications.

Current Workaround

Users currently work around this by:

• Typing clear command
• Using Ctrl+L doesn't work (as mentioned in #1341 where users manually clear with Ctrl+L)

Benefits

• Improved user experience and muscle memory consistency
• Faster terminal clearing without typing commands
• Standard terminal behavior users expect

Additional Context

This would complement the existing /clear command (mentioned in #1561) and provide a more intuitive keyboard shortcut for the same functionality.