fix: use Gitea API for version check instead of GitHub

backend/internal/repository/github_release_service.go

@@ -76,13 +76,14 @@ func (c *githubReleaseClientError) FetchChecksumFile(ctx context.Context, url st
 }
 
 func (c *githubReleaseClient) FetchLatestRelease(ctx context.Context, repo string) (*service.GitHubRelease, error) {
-	url := fmt.Sprintf("https://api.github.com/repos/%s/releases/latest", repo)
+	// 使用 Gitea API（兼容 GitHub Release API 格式）
+	url := fmt.Sprintf("http://git.jianshixingqiu.com/api/v1/repos/%s/releases/latest", repo)
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("Accept", "application/vnd.github.v3+json")
+	req.Header.Set("Accept", "application/json")
 	req.Header.Set("User-Agent", "Sub2API-Updater")
 
 	resp, err := c.httpClient.Do(req)
@@ -92,7 +93,7 @@ func (c *githubReleaseClient) FetchLatestRelease(ctx context.Context, repo strin
 	defer func() { _ = resp.Body.Close() }()
 
 	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("GitHub API returned %d", resp.StatusCode)
+		return nil, fmt.Errorf("Gitea API returned %d", resp.StatusCode)
 	}
 
 	var release service.GitHubRelease