feat(scanner): add Scanner.FollowSymlinks option (#4061)

* Add Scanner.FollowSymlinks option (default: true) - Fixes #4060

* fix(mockMusicFS): improve symlink handling in Open, Stat, and ReadDir methods

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(tests): enhance walkDirTree tests with symlink handling and cleanup

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

scanner/walk_dir_tree.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/navidrome/navidrome/conf"
 	"github.com/navidrome/navidrome/consts"
 	"github.com/navidrome/navidrome/core"
 	"github.com/navidrome/navidrome/log"
@@ -266,6 +267,10 @@ func isDirOrSymlinkToDir(fsys fs.FS, baseDir string, dirEnt fs.DirEntry) (bool,
 	if dirEnt.Type()&fs.ModeSymlink == 0 {
 		return false, nil
 	}
+	// If symlinks are disabled, return false for symlinks
+	if !conf.Server.Scanner.FollowSymlinks {
+		return false, nil
+	}
 	// Does this symlink point to a directory?
 	fileInfo, err := fs.Stat(fsys, path.Join(baseDir, dirEnt.Name()))
 	if err != nil {