Remove incorrect mermaid diagram from Chat introduction

The architecture flowchart was misleading and low quality; the table
above it already covers the pieces apps need.

Author: tcaldwell-x

xchat/introduction.mdx

@@ -17,14 +17,6 @@ The **Chat API** lets you send and receive **end-to-end encrypted** direct messa
 | **X API access** | Public keys, conversation keys, messages, events, media—via **[XDK](/xdks/python/overview)** (Python/TypeScript) or HTTPS |
 | **Delivery** | [Webhooks or activity stream](/xchat/real-time-events) for live events; events API for history |
 
-```mermaid
-flowchart LR
-    A[Chat XDK] --> B[Your app]
-    B --> C[X API]
-    C --> D[Webhook / stream]
-    D --> A
-```
-
 Follow **[Getting Started](/xchat/getting-started)** for a full implementation. For concepts only, see the **[Cryptography primer](/xchat/cryptography-primer)**.
 
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