fix: translate qBittorrent container paths for auto-organize

- Add path translation for cross-container download paths
- Map common qBittorrent container paths to /downloads
- Fixes 'payload path is not accessible' warnings in logs
- Enables auto-organize to work when qBittorrent runs in separate container

internal/service/path_translation.go

@@ -0,0 +1,30 @@
+package service
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// translateClientPath 将下载客户端报告的路径转换为容器内可访问的路径。
+// 常见场景：qBittorrent在另一个容器，报告的路径是其容器内路径，需要映射到当前容器。
+func translateClientPath(clientPath string, mappings map[string]string) string {
+	if clientPath == "" {
+		return ""
+	}
+	clean := filepath.Clean(clientPath)
+	// 尝试直接访问
+	if _, err := os.Stat(clean); err == nil {
+		return clean
+	}
+	// 尝试路径映射
+	for clientPrefix, localPrefix := range mappings {
+		if strings.HasPrefix(clean, clientPrefix) {
+			translated := filepath.Join(localPrefix, strings.TrimPrefix(clean, clientPrefix))
+			if _, err := os.Stat(translated); err == nil {
+				return translated
+			}
+		}
+	}
+	return ""
+}