Extract agent, compact, embed, task, and modes modules from single
service.rs files into focused sub-modules. Add orao module for
O1-like reasoning loop. Move RigAgentService to rig_tool.rs.
Add persistent chat session state (ChatState, sequence tracking, tool
calls). Introduce basic billing record in agent crate. Refine chat
service to route messages through state machine with tool support.
- Use AgentBuilder for native tool-calling with stream_prompt()
- Add RecordingTool wrapper preserving retry + DB recording
- Fix tool_choice bug in do_completion (same as call_stream_once)
- Add seq field to RoomMessageStreamChunkEvent for strict ordering
- Map streaming events: Text→Answer, Reasoning→Thought, ToolCall→Action
- Only final event has done=true, removed premature stream ending
- Store __chunks__ JSON in thinking_content for ordered replay
- StreamChunk/StreamChunkType types for preserving arrival order
- Chunk collection in call_stream_once and process_stream
- Add "error sending request" and "Http client error" to retryable errors
- StreamResult includes chunks vector for ordered replay
