feat: Update ManagerAgent to clarify tool usage in hierarchical mode

feat: Implement structured report generation with validation and markdown output

Add ResearcherAgent class for qualitative market research and sentiment analysis

Add ReporterAgent class for investment report synthesis and management

Add ManagerAgent class to orchestrate research workflow and task delegation

Add base agent factory and utilities for agent creation and configuration loading

Add AnalystAgent class for quantitative financial analysis in FinResearch AI

Add __init__.py for agents module in FinResearch AI, defining agent imports and module exports