Extract core LLM tool loop logic into shared RunToolLoop function that can be
used by both main agent and subagents. Subagents now run their own tool loop
with dedicated tool registry, enabling full independence.
Key changes:
- New pkg/tools/toolloop.go with reusable tool execution logic
- Subagents use message tool to communicate directly with users
- Heartbeat processing is now stateless via ProcessHeartbeat
- Simplified system message routing without result forwarding
- Shared tool registry creation for consistency between agents
This architecture follows openclaw's design where async tools notify via
bus and subagents handle their own user communication.
0cce9fc905