Docs: rework README into a business-first MCP landing page

[itprodirect]

Objective

Rework the repository landing experience so a first-time, non-technical business user can understand what MCP is, why it matters, and what they can safely try in this repo.

Context

The repo already has setup steps, CLI examples, notebook references, screenshots, a glossary, and common issues. The next improvement should be positioning: make the README feel like a clear learning product instead of a developer scratchpad.

Scope

• Update README.md.
• Add docs/00-start-here.md if it helps keep the README concise.
• Fix obviously incorrect or placeholder MCP links in AGENTS.md.
• Preserve the existing Python package, CLI examples, notebook references, and sample-data workflow.

Acceptance criteria

• README explains MCP in plain English.
• README clearly says MCP is not an AI model, not magic automation, and not automatically secure.
• README includes a simple visual/text diagram such as Business Question -> AI Host -> MCP Client -> MCP Server -> Tool/Data -> Answer.
• README includes a "choose your path" section for business users, beginners, and developers.
• README includes a clear warning to use sample data only and avoid real client data in tutorial demos.
• Existing install/run/test commands are still present and copy/paste friendly.
• No business logic, package code, or sample data changes are included.

Non-goals

• Do not add a web app.
• Do not add MCPB packaging.
• Do not add claims automation code.
• Do not introduce new runtime dependencies.

Validation

Run the existing quality gate even though this should be docs-focused:

ruff check .
mypy --strict .
pytest -q

Suggested Codex /goal summary

Improve the README and beginner entry docs so regular business users understand MCP, while preserving the existing CLI/package/test behavior.

[stevesagronegocios673-ux]

This scope is larger than a quick PR, but I can do a tiny $5 positioning pass first: 5 concrete README edits plus one sample rewrite for the intro / “choose your path” section, focused on business users. If useful, I’ll keep it as review notes before any implementation.