feat(research): configurable agent interval + MCP hot_money_server rename + deps cleanup

[onmyway0011]

This PR introduces several improvements:

1. Research improvements

• Add agent_interval_seconds to ResearchEnvironment and CLI --agent-interval to configure inter-agent wait time
• Replace hardcoded 3s delay with configurable interval, update visual messages accordingly

2. MCP fixes

• Rename misspelled src/mcp/hot_money_srver.py to src/mcp/hot_money_server.py

3. Dependencies cleanup

• Remove unused streamlit, asyncio
• Remove duplicate duckduckgo-search entry and keep duckduckgo_search~=7.5.3

Tested

• CLI help renders --agent-interval
• Research environment uses configured interval in logs and visualizer

Notes

• Runtime requires Python 3.11+ since Pydantic v2 is used; Python 3.10 will raise ImportError: cannot import name 'model_validator'

Thank you for your review!