Add a new "analysis" step type to handle reasoning and synthesis tasks
that don't require code execution, addressing the concern that routing
all non-search tasks to the coder agent was inappropriate.
Changes:
- Add ANALYSIS enum value to StepType in planner_model.py
- Create analyst_node for pure LLM reasoning without tools
- Update graph routing to route analysis steps to analyst agent
- Add analyst agent to AGENT_LLM_MAP configuration
- Create analyst prompts (English and Chinese)
- Update planner prompts with guidance on choosing between
analysis (reasoning/synthesis) and processing (code execution)
- Change default step_type inference from "processing" to "analysis"
when need_search=false
Co-authored-by: Willem Jiang <143703838+willem-bd@users.noreply.github.com>