IME Enter key bypasses keybindings in Confirmation UI (Plan comments, AskUserQuestion)

Description

The fix for IME Enter key handling (PR #8480) resolved the issue in the main chat input, but the same problem persists in Confirmation-context UI dialogs in the desktop app.

Affected Areas

• Plan mode comment input — the text field shown via "Tell Claude what to do instead" (代わりにClaudeに何をすべきか指示する)
• AskUserQuestion "Other" text input — when typing a custom response to agent questions

Steps to Reproduce

1. Use Japanese IME (or other CJK IME) on macOS
2. Enter plan mode and get a plan proposal
3. Select "Tell Claude what to do instead" to type feedback
4. Type Japanese text and press Enter to confirm IME conversion
5. Actual: The Enter key is captured as submission (confirm:yes), sending the incomplete/unintended message
6. Expected: Enter only confirms IME composition; a separate key (e.g., Cmd+Enter) submits

Same behavior occurs in the AskUserQuestion "Other" text input.

Workaround Attempted

Setting "enter": null in the Confirmation context via ~/.claude/keybindings.json has no effect, suggesting the Enter handler in these dialogs bypasses the keybinding system:

{
  "bindings": [
    {
      "context": "Confirmation",
      "bindings": {
        "enter": null,
        "meta+enter": "confirm:yes"
      }
    }
  ]
}

Environment

• Claude Code v2.1.76 (Desktop App, macOS)
• macOS Japanese IME

Context

• Related: #8405 (locked), PR #8480 (fix for chat input)
• The main chat input (Chat context) works correctly after the fix — this issue is isolated to Confirmation-context dialogs
• Many Japanese users have reported the general IME Enter issue on X/Twitter, but those reports are primarily about chat input / VS Code extension, which are now fixed