docs: 将系统架构图改为 Mermaid 格式

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -42,17 +42,26 @@ awsl-one-api/
 
 ## 🏗️ 系统架构
 
-```text
-┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
-│  Client Apps    │───▶│  AWSL One API   │───▶│  AI Providers   │
-│                 │    │  (CF Workers)   │    │(Azure OpenAI &  │
-└─────────────────┘    └─────────────────┘    │    OpenAI)      │
-                              │                └─────────────────┘
-                              ▼
-                       ┌─────────────────┐
-                       │  Cloudflare D1  │
-                       │    Database     │
-                       └─────────────────┘
+```mermaid
+flowchart LR
+    subgraph Clients["客户端"]
+        A[Client Apps]
+    end
+
+    subgraph CF["Cloudflare Workers"]
+        B[AWSL One API]
+        D[(Cloudflare D1<br/>Database)]
+    end
+
+    subgraph Providers["AI 服务提供商"]
+        C1[Azure OpenAI]
+        C2[OpenAI]
+    end
+
+    A -->|API Request| B
+    B -->|Proxy| C1
+    B -->|Proxy| C2
+    B <-->|Read/Write| D
 ```
 
 ## 🚀 快速开始