VSCode extension: keybindings 'enter' override not working correctly

Bug Description

In the VSCode extension, overriding the enter key in ~/.claude/keybindings.json does not work correctly.

Reproduction Steps

Case 1: "enter": null

Setting enter to null completely disables the Enter key — neither newline nor submit works.

{
  "bindings": [
    {
      "context": "Chat",
      "bindings": {
        "enter": null,
        "alt+enter": "chat:submit"
      }
    }
  ]
}

Expected: Enter key is unbound (no submit), but other functionality (e.g., newline) still works.
Actual: Enter key does nothing at all — no newline, no submit.

Case 2: "enter": "chat:newline"

Setting enter to chat:newline causes both newline and submit to fire simultaneously.

{
  "bindings": [
    {
      "context": "Chat",
      "bindings": {
        "enter": "chat:newline",
        "alt+enter": "chat:submit"
      }
    }
  ]
}

Expected: Enter key only inserts a newline (no submit).
Actual: Enter key inserts a newline AND submits the message at the same time.

Environment

• VSCode extension (not terminal CLI)
• Linux (WSL2)

Use Case

Trying to remap Enter to newline-only and use Alt+Enter (or Ctrl+Enter) for submit, similar to how Slack/Discord work.