C# AI Receptionist Automation

I need a fully-functional AI receptionist built in pure C#. The application must continuously read incoming direct messages from the major social networks, interpret the intent, reply in natural language—either as plain text or synthesized voice—and, when appropriate, secure an appointment for the sender.

Core requirements
• Social inbox monitoring: poll or stream the APIs of Facebook, Twitter and Instagram and whatsapp (and leave the code structured so additional channels can be plugged in later).
• Natural-language understanding: leverage an LLM or service such as Azure OpenAI, then drive the conversation flow according to my configurable rules.
• Voice layer: integrate Microsoft Cognitive Services (or a comparable .NET-friendly engine) so replies can be spoken as well as typed.
• Appointment handling: once the user confirms a time, the bot must write straight to my Microsoft 365 calendar; if that API is unavailable it should fall back to sending a confirmation email.
• Admin dashboard: WinForms, WPF or Blazor—your choice—as long as I can see message logs, override replies and tweak intents without touching code.

Deliverables
1. Complete Visual Studio solution with clean, documented C# source.
2. Step-by-step setup notes covering API keys, webhook endpoints and any Azure resources.
3. A short screen-capture demo showing the bot replying in both modalities and creating a live calendar event.

Acceptance will be based on a 15-minute test session in which I send sample messages from each social platform, hear a spoken acknowledgment and receive an appointment in my calendar.