[BUG] Option+Backspace word deletion broken after v2.1.0 terminal keyboard changes

Description

After upgrading to v2.1.0, Option+Backspace no longer deletes words - it deletes single characters instead. This appears to be a regression from the terminal keyboard mode changes that made Shift+Enter work natively.

Expected Behaviour

Option+Backspace should delete the word before the cursor (standard macOS text editing behaviour).

Actual Behaviour

Option+Backspace deletes only a single character, same as regular Backspace.

Likely Cause

The v2.1.0 release notes mention:

• "Changed Shift+Enter to work out of the box in iTerm2, WezTerm, Ghostty, and Kitty without modifying terminal configs"
• "Fixed Alt+B and Alt+F (word navigation) not working in iTerm2, Ghostty, Kitty, and WezTerm"

The keyboard mode changes that enabled native Shift+Enter appear to have broken Option+Backspace as a side effect. Word navigation (Alt+B/Alt+F) was fixed, but word deletion (Option+Backspace) was not addressed and now appears broken.

Environment

• Platform: macOS (darwin)
• Terminal: Ghostty
• Claude Code Version: 2.1.x

Additional Context

Previously, /terminal-setup would configure the terminal for both Shift+Enter multiline input AND preserve Option+Backspace word deletion. With Shift+Enter now being native, the terminal configuration that enabled Option+Backspace appears to have been lost.