Feature - Extend the Market Trend AI Agent use cases with a new UI and memory integration

[deepaxs]

I needed to extend the market trend AI agent use case for a customer demo, so would like this new code base to update the current code base for market trend ai agent.
Extends the market-trends-agent use case with LangGraph AgentCore Memory checkpointer and store integration, a React chat UI, and a FastAPI backend proxy — creating a full-stack demo of personalized financial intelligence with persistent broker profiles.