feat(update): 添加在线更新和定价数据获取的代理支持

针对国内服务器访问 GitHub 困难的问题，为在线更新和定价数据获取功能添加代理支持。

主要变更：
- 新增 update.proxy_url 配置项，支持 http/https/socks5/socks5h 协议
- 修改 GitHubReleaseClient 和 PricingRemoteClient 支持代理配置
- 更新 Wire 依赖注入，通过 Provider 函数传递配置
- 更新 Docker 配置文件，支持通过 UPDATE_PROXY_URL 环境变量设置代理

配置示例：
  update:
    proxy_url: "http://127.0.0.1:7890"

Docker 环境变量：
  UPDATE_PROXY_URL=http://host.docker.internal:7890

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/internal/repository/github_release_service.go

@@ -14,23 +14,33 @@ import (
 )
 
 type githubReleaseClient struct {
-	httpClient        *http.Client
-	allowPrivateHosts bool
+	httpClient         *http.Client
+	downloadHTTPClient *http.Client
 }
 
-func NewGitHubReleaseClient() service.GitHubReleaseClient {
-	allowPrivate := false
+// NewGitHubReleaseClient 创建 GitHub Release 客户端
+// proxyURL 为空时直连 GitHub，支持 http/https/socks5/socks5h 协议
+func NewGitHubReleaseClient(proxyURL string) service.GitHubReleaseClient {
 	sharedClient, err := httpclient.GetClient(httpclient.Options{
-		Timeout:            30 * time.Second,
-		ValidateResolvedIP: true,
-		AllowPrivateHosts:  allowPrivate,
+		Timeout:  30 * time.Second,
+		ProxyURL: proxyURL,
 	})
 	if err != nil {
 		sharedClient = &http.Client{Timeout: 30 * time.Second}
 	}
+
+	// 下载客户端需要更长的超时时间
+	downloadClient, err := httpclient.GetClient(httpclient.Options{
+		Timeout:  10 * time.Minute,
+		ProxyURL: proxyURL,
+	})
+	if err != nil {
+		downloadClient = &http.Client{Timeout: 10 * time.Minute}
+	}
+
 	return &githubReleaseClient{
-		httpClient:        sharedClient,
-		allowPrivateHosts: allowPrivate,
+		httpClient:         sharedClient,
+		downloadHTTPClient: downloadClient,
 	}
 }
 
@@ -68,15 +78,8 @@ func (c *githubReleaseClient) DownloadFile(ctx context.Context, url, dest string
 		return err
 	}
 
-	downloadClient, err := httpclient.GetClient(httpclient.Options{
-		Timeout:            10 * time.Minute,
-		ValidateResolvedIP: true,
-		AllowPrivateHosts:  c.allowPrivateHosts,
-	})
-	if err != nil {
-		downloadClient = &http.Client{Timeout: 10 * time.Minute}
-	}
-	resp, err := downloadClient.Do(req)
+	// 使用预配置的下载客户端（已包含代理配置）
+	resp, err := c.downloadHTTPClient.Do(req)
 	if err != nil {
 		return err
 	}