Fix scan-library path to work in both development and production

- Auto-detect music library path based on environment
- Check for music/library/ directory for local development
- Default to /app/music/ for production Docker deployment
- Allow MUSIC_LIBRARY_PATH environment variable override
- Fixes scan-library function failing on production server

asteroid.lisp

@@ -17,7 +17,10 @@
 (defparameter *server-port* 8080)
 (defparameter *music-library-path* 
   (or (uiop:getenv "MUSIC_LIBRARY_PATH")
-      "/app/music/"))
+      ;; Default to /app/music/ for production Docker, but check if music/library/ exists for local dev
+      (if (probe-file (merge-pathnames "music/library/" (asdf:system-source-directory :asteroid)))
+          (merge-pathnames "music/library/" (asdf:system-source-directory :asteroid))
+          "/app/music/")))
 (defparameter *supported-formats* '("mp3" "flac" "ogg" "wav"))
 (defparameter *stream-base-url* "http://localhost:8000")