Gives Navidrome access to the media directory

This matches other media add-ons in this repo and lets Navidrome access the default store for media.

navidrome/config.json

@@ -9,6 +9,7 @@
   "init": false,
   "map": [
     "addon_config:rw",
+    "media:rw",
     "share:rw",
     "ssl:rw"
   ],