feat: 支持多区域配置的Cloudflare Gateway URL

多区域支持:
- 将region改为regions字符串数组
- 支持多个区域: us-central1, us-east1, europe-west1
- 使用第一个区域作为默认区域
- 添加区域选择的详细日志

 Cloudflare Gateway URL格式:
- 完整的URL构建逻辑
- 格式: https://gateway.ai.cloudflare.com/v1/{project_id}/{gateway_id}/google-vertex-ai/v1/projects/{google_project_id}/locations/{region}/publishers/google/models
- 支持动态区域切换

 配置参数:
- cloudflare_project_id: 67720b647ff2b55cf37ba3ef9e677083
- cloudflare_gateway_id: bowong-dev
- google_project_id: gen-lang-client-0413414134
- regions: [us-central1, us-east1, europe-west1]

 日志增强:
- 显示构建的完整Gateway URL
- 显示当前使用的区域
- 显示所有可用区域列表

现在支持标准的Cloudflare Gateway多区域配置。

apps/desktop/src-tauri/src/infrastructure/gemini_service.rs

@@ -17,6 +17,10 @@ pub struct GeminiConfig {
     pub retry_delay: u64,
     pub temperature: f32,
     pub max_tokens: u32,
+    pub cloudflare_project_id: String,
+    pub cloudflare_gateway_id: String,
+    pub google_project_id: String,
+    pub regions: Vec<String>,
 }
 
 impl Default for GeminiConfig {
@@ -30,6 +34,14 @@ impl Default for GeminiConfig {
             retry_delay: 2,
             temperature: 0.1,
             max_tokens: 2048,
+            cloudflare_project_id: "67720b647ff2b55cf37ba3ef9e677083".to_string(),
+            cloudflare_gateway_id: "bowong-dev".to_string(),
+            google_project_id: "gen-lang-client-0413414134".to_string(),
+            regions: vec![
+                "us-central1".to_string(),
+                "us-east1".to_string(),
+                "europe-west1".to_string(),
+            ],
         }
     }
 }
@@ -209,8 +221,26 @@ impl GeminiService {
         headers.insert("Authorization".to_string(), format!("Bearer {}", access_token));
         headers.insert("Content-Type".to_string(), "application/json".to_string());
 
+        // 使用第一个区域作为默认区域
+        let region = self.config.regions.first()
+            .unwrap_or(&"us-central1".to_string())
+            .clone();
+
+        // 构建Cloudflare Gateway URL
+        let gateway_url = format!(
+            "https://gateway.ai.cloudflare.com/v1/{}/{}/google-vertex-ai/v1/projects/{}/locations/{}/publishers/google/models",
+            self.config.cloudflare_project_id,
+            self.config.cloudflare_gateway_id,
+            self.config.google_project_id,
+            region
+        );
+
+        println!("🔗 构建的Cloudflare Gateway URL: {}", gateway_url);
+        println!("🌍 使用的区域: {}", region);
+        println!("📋 可用区域: {:?}", self.config.regions);
+
         ClientConfig {
-            gateway_url: self.config.base_url.clone(),
+            gateway_url,
             headers,
         }
     }