fix: add spacing between tool calls and assistant message in streaming

When tool calls appeared followed by an assistant message during streaming,
there was insufficient spacing between '(co is updating memory)' and
'(co is saying)', making them appear cramped.

Changes:
- Add 16px marginTop to LiveStatusIndicator when tool calls precede it
- Wrap LiveStatusIndicator in View with conditional margin
- Only apply margin when currentStream.toolCalls.length > 0

This improves visual separation between streaming tool calls and the
subsequent assistant message.