Update Lab 001 with e2e testing improvements

[BethanyJep]

Here’s an updated PR description that follows your template and references the changes above:

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Description

This PR updates the workshop onboarding documentation for the "Explain Like I'm an Executive" hosted agent lab. It simplifies and modernizes the prerequisites and setup instructions, clarifies the difference between Azure and local/free-tier paths, and aligns terminology and environment variable naming with current Foundry conventions.

Closes #

Type of Change

• Documentation update
• Bug fix
• New feature
• Refactor / code improvement
• CI / tooling change

Changes Made

• Rewrote 00-prerequisites.md as a concise "Introduction" with clear path selection (Azure cloud vs. local/free-tier), tool matrix, and simplified instructions.
• Moved and condensed extension installation and verification into a new 01-setup.md (replaces the old 01-install-foundry-toolkit.md), with clear step-by-step guidance for both Azure and local paths.
• Updated .env.example to use AZURE_AI_MODEL_DEPLOYMENT_NAME (was MODEL_DEPLOYMENT_NAME) for consistency with environment variable naming conventions.
• Added diagrams and improved explanations for key concepts (hosted agents, Agent Inspector, etc).
• Clarified RBAC requirements and added explicit callouts for the "Azure AI User" role.
• Provided explicit checkpoints for each step and ensured all instructions are actionable and up-to-date.

Testing

Describe how you tested your changes.

• Ran workshop lab01 locally
• Verified documentation renders correctly in VS Code and GitHub
• Stepped through both Azure and local/free-tier setup paths to ensure clarity and completeness
• Tested with Agent Inspector
• Updated / added documentation where applicable

Checklist

• My changes follow the workshop conventions
• No secrets or credentials have been committed
• Documentation updated if behaviour changed
• PR title is descriptive and references the issue (e.g. docs: update lab01 prerequisites #5)

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Context:
This PR is a documentation update that streamlines onboarding for the hosted agent workshop. It replaces the previous, lengthy prerequisites and extension installation modules with a more approachable, path-based introduction and setup. It also ensures environment variable naming is consistent with Foundry conventions (AZURE_AI_MODEL_DEPLOYMENT_NAME). The goal is to reduce friction for both Azure and non-Azure users, clarify RBAC requirements, and provide clear checkpoints for each setup step.