Add mcs policy agent da

[keshavk-msft]

What's in this PR

Adds a new sample: samples/mcs-policy-agent-da — Policy Agent (Declarative Agent) for Microsoft Copilot Studio.

A SharePoint-grounded Declarative Agent that gives employees quick, summary-level answers to HR / IT / Finance policy questions — using Microsoft 365 grounding for fast time-to-value and minimal configuration. The agent returns multi-file referenced summaries instead of forcing users to dig through SharePoint sites.

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/SharePointSearchSource.0.mcs.yml — SharePoint knowledge source
  • topics/OnError.mcs.yml — global error topic

Notes

• Sample was exported from Copilot Studio using the VS Code extension (.mcs.yml source format).
• All tenant-specific SharePoint URLs are replaced with 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