Add Agentic Mode(ReAct Agent) in research agent & use its tools in MCP Impl

Well, I’m traveling this weekend, but over the next week I’ll be working on implementing Agentic Mode (ReAct Agent) in the research agent. Our deterministic researcher agent is good enough now; it’s time to add the latest trends and maybe anticipate the future.

The initial PR will be from me, but hopefully people with more experience can pick it up after the base PR.
