Fix SBCL bracket-escaping in shuffle library scanner

stream-harmony.lisp:
- scan-music-library-files: use native-namestring instead of namestring
  when collecting file paths, producing real OS paths without SBCL's
  backslash escaping of brackets (e.g. [FLAC] not \[FLAC])
- Use parse-native-namestring for root directory entry point so dirs
  with brackets are not treated as wildcard patterns

cl-streamer submodule updated to d57a268:
- play-file, read-audio-metadata, play-list retry: same native-namestring
  fix to prevent double-escaping through parse-native-namestring

Fixes FLAC FILE slot unbound errors and SIGSEGV memory fault that
crashed the shuffle pipeline after consecutive failures on bracket paths.

cl-streamer

@@ -1 +1 @@
-Subproject commit c0f9c0e161e2076f7dde8fdcbcb0f701d02cc35b
+Subproject commit d57a2683e757577a7292b63b5d3ad7016bb24187

stream-harmony.lisp

@@ -307,7 +307,8 @@
 
 (defun scan-music-library-files (&optional (directory *music-library-path*))
   "Recursively scan DIRECTORY for supported audio files.
-   Returns a list of namestrings."
+   Returns a list of native namestrings (real OS paths without SBCL's
+   bracket escaping, safe to pass through parse-native-namestring later)."
   (let ((files nil)
         (extensions *supported-formats*))
     (labels ((scan (dir)
@@ -315,7 +316,7 @@
                    (dolist (entry (uiop:directory-files dir))
                      (let ((ext (pathname-type entry)))
                        (when (and ext (member ext extensions :test #'string-equal))
-                         (push (namestring entry) files))))
+                         (push (sb-ext:native-namestring entry) files))))
                  (error (e)
                    (log:debug "Error scanning ~A: ~A" dir e)))
                (handler-case
@@ -323,7 +324,14 @@
                      (scan sub))
                  (error (e)
                    (log:debug "Error listing subdirs of ~A: ~A" dir e)))))
-      (scan (pathname directory)))
+      ;; Use parse-native-namestring so directories with brackets (e.g.
+      ;; "[FLAC]") are not treated as wildcard patterns by SBCL.
+      (scan (sb-ext:parse-native-namestring
+             (etypecase directory
+               (string directory)
+               (pathname (sb-ext:native-namestring directory)))
+             nil *default-pathname-defaults*
+             :as-directory t)))
     (nreverse files)))
 
 (defvar *shuffle-library-cache* nil