Users can submit messages with the Enter key

Forcing users to mouse over to a send button for every message is both slow and jarring — it breaks the typing flow that everyone has been trained on by every messaging product in existence. Keyboard power users will bounce off a chat interface that requires a click per submit, and on tablet and laptop users the friction accumulates across hundreds of messages per session. This also affects accessibility: users who rely on keyboard-only navigation per WCAG 2.2 SC 2.1.1 (Keyboard) must have a keyboard submit path.

In src/components/chat/ChatInput.tsx, add an onKeyDown handler that submits on Enter (without Shift), prevents the default newline, guards against empty input and in-flight generation, and reserves Shift+Enter for newline. Surface the shortcut with a visible hint near the input.

onKeyDown={(e) => {
  if (e.key === 'Enter' && !e.shiftKey) {
    e.preventDefault();
    if (!isLoading && input.trim()) handleSubmit(e);
  }
}}