Agentic UI: Chat, Tools, Questions

[shaunandrews]

This PR builds on #3646, adding:

• More human Tool calls descriptions in the conversation, with icons.
• Clicking a tool call opens more details with a scrollable container for longer details.
• Ask User tool calls show the possible options with descriptions as an ordered list.
• Status indicators in the sidebar help you know when the agent is working (pulsing dot), awaiting your response (orange square), or finished (static dot).