fix: make qbittorrent login compatible

internal/service/download_clients.go

@@ -8,9 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"net/http"
-	"net/url"
 	"strings"
 	"time"
 
@@ -130,40 +128,7 @@ func (s *DownloadClientService) Test(ctx context.Context, id string) error {
 	}
 	switch c.Type {
 	case "qbittorrent":
-		host := strings.TrimRight(c.Host, "/")
-		body := url.Values{}
-		body.Set("username", c.Username)
-		body.Set("password", c.Password)
-		req, _ := http.NewRequestWithContext(
-			ctx, http.MethodPost,
-			host+"/api/v2/auth/login",
-			strings.NewReader(body.Encode()),
-		)
-		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-		// qBittorrent v4.6+ 默认开启 "host header validation" 并要求
-		// Referer 与 Host 同源，否则即使账户正确也会拒绝登录。
-		req.Header.Set("Referer", host)
-		req.Header.Set("Origin", host)
-		req.Header.Set("User-Agent", "MediaStationGo/0.1")
-		resp, err := s.client.Do(req)
-		if err != nil {
-			return err
-		}
-		defer resp.Body.Close()
-		if resp.StatusCode == http.StatusForbidden {
-			return errors.New("qbittorrent: 403 — 用户名/密码错误，或 WebUI 启用了 IP 封禁")
-		}
-		if resp.StatusCode >= 400 {
-			return fmt.Errorf("qbittorrent returned %d", resp.StatusCode)
-		}
-		// 即使返回 200，body 内容仍可能是 "Fails." 表示登录失败。
-		raw, _ := io.ReadAll(io.LimitReader(resp.Body, 256))
-		text := strings.TrimSpace(string(raw))
-		if text == "Fails." {
-			return errors.New("qbittorrent: 用户名/密码错误")
-		}
-		// 正确响应是 "Ok." — 但部分版本会重定向或返回空体，不强校验。
-		return nil
+		return qbitLogin(ctx, s.client, c.Host, c.Username, c.Password)
 	case "aria2", "transmission":
 		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, c.Host, nil)
 		resp, err := s.client.Do(req)