Microsoft AI guidance: Migrate to Microsoft MCP package

[souvikghosh04]

Migrate DAB's MCP layer from the community SDK (ModelContextProtocol 0.3.0-preview.4) to Microsoft's official Microsoft.ModelContextProtocol.HttpServer (0.1.0-preview.25). This positions DAB for future Entra ID authentication, MISE integration, rate limiting, and first-party OpenTelemetry support.