Feature request: add chat:deleteWordBackward action for option+backspace word deletion

Feature Request

Summary: Add a chat:deleteWordBackward (and optionally chat:deleteWordForward) action to the keybinding system so users can bind word-deletion shortcuts like option+backspace.

Current behavior: option+backspace does nothing in Claude Code's chat input, even when the same shortcut works in the surrounding terminal (e.g. Warp). There is no word-deletion action exposed in the keybinding system to map it to.

Desired behavior: A chat:deleteWordBackward action that users can bind via ~/.claude/keybindings.json:

\\\json
{
"$schema": "https://www.schemastore.org/claude-code-keybindings.json",
"$docs": "https://code.claude.com/docs/en/keybindings",
"bindings": [
{
"context": "Chat",
"bindings": {
"alt+backspace": "chat:deleteWordBackward"
}
}
]
}
\\\

Workaround: ctrl+w works for word deletion but is not rebindable to the preferred shortcut.