Add mcs policy agent cea

[keshavk-msft]

What's in this PR

Adds a new sample: samples/mcs-policy-agent-cea — Policy Agent (Custom Engine Agent with Escalation) for Microsoft Copilot Studio.

A Custom Engine Agent that answers HR / IT / Finance policy questions from a SharePoint knowledge source, and escalates detailed clause-level requests to Salesforce through an Agent Flow — keeping the conversation in one place.

Contents

• README.md — problem statement, architecture, sample prompts, deployment steps
• assets/sample.json — PnP sample gallery metadata (with demo video thumbnail)
• src/ — Copilot Studio agent source (.mcs.yml):
  • agent.mcs.yml, settings.mcs.yml
  • knowledge/ — SharePoint knowledge source
  • topics/ — full topic set (Greeting, Fallback, Escalate, Search, Signin, …)
  • actions/SalesforceFlow.mcs.yml — declarative action calling the escalation flow
  • workflows/SalesforceFlow-…/ — Agent Flow that talks to Salesforce

Notes

• Sample was exported from Copilot Studio using the VS Code extension (.mcs.yml source format).
• All tenant-specific values (SharePoint host, Salesforce Consumer Key / Secret / Username / Security Token, org instance URL) are replaced with <YOUR_…> / contoso.sharepoint.com placeholders — reviewers can confirm via the diff.
• Demo video is embedded in the README via a GitHub user-attachments URL.
• I have signed the Microsoft CLA.

Checklist

• One sample per PR (per CONTRIBUTING.md)
• README.md present at sample root
• assets/sample.json present
• No secrets or tenant-specific values committed
• Static screenshot in assets/ — to be added; demo video link included in the meantime