Use different spinner indicators for "agent processing" vs "waiting for user input"

[JJJessieWang]

When the agent is running and when it's waiting for user input, the terminal shows the same spinning indicator. After a notification sound plays (e.g., when a background task or sub-agent completes), I can't tell at a glance which session has finished and needs my attention — they all look the same.

Proposed Solution. Use visually distinct indicators for the two states:

• Agent processing — keep the current spinner (e.g., ⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏)
• Waiting for user input — use a different visual, such as a blinking ?, or a ear 👂, or a distinct color/icon

Thanks!!