feat: mount Flask WSGI + Gradio on unified FastAPI ASGI app

feat: add Gradio entrypoint, Caddy reverse proxy, and SLM integration

refactor!: hosted-model-only core, Drive report delivery, shared harnesses

refactor: modernize codebase to Pure Agentic RAG with live Vercel REST tools and Google Python Style Guide standards

Restructured the directory structure and updated coding format as PEP8