create agent status indicators

[mattjdavis]

track tool use, tokens, and agent activity for good user experience.

[mattjdavis]

Implementation details

🟢 Idle / 🟡 Thinking / 🔵 Working / 🔴 Error
Pulsing animation while agent is active
Current Activity Panel

Shows real-time tool execution: "Executing: ng_add_annotation"
Tool chain display: "Tools: query_data → ng_add_annotation → ng_set_view"
Clears to "Ready" when idle
Token Usage Counters

Current response: "🎯 This response: 1,234 tokens (500 prompt + 734 completion)"
Session total: "📊 Total conversation: 15,678 tokens"
Persists across messages, accumulates session totals
Status Messages (abbreviated)

Replace long Neuroglancer URLs with: "✓ State loaded" or "🔗 View updated"
Keep error messages verbose for debugging

[mattjdavis]

added activity indicator + token usage above chat