Ctrl+Backspace (delete previous word) doesn't work on Windows

Ctrl+Backspace does nothing in the CLI input prompt on Windows. This is the standard shortcut for "delete previous word" in every other Windows text input (browsers, VS Code, Notepad, shell prompts).

Alt+Backspace works as a workaround, but that's the Unix/macOS convention — not what Windows users reach for.

Windows Terminal's  sendInput  remapping can't fix this either, because the CLI reads raw key events with modifier flags rather than character input.

Likely a small fix — just add Ctrl+Backspace alongside the existing Alt+Backspace handler in the input library.

Environment: Windows 11, Windows Terminal, Copilot CLI 1.0.64-0

Start at the CLI input library's existing Alt+Backspace handler and inspect how raw key events and modifier flags are matched on Windows. Add the equivalent Ctrl+Backspace behavior, then verify that it deletes the previous word in the Windows CLI prompt while preserving the existing Alt+Backspace behavior.

索引モデルが issue の本文から書いたものです。