fix: Playlists Pagination + Player Fehlermeldungen

- Playlists: Alle werden jetzt geladen (Pagination)
- Player: Fehlermeldung wenn kein Geraet aktiv
- next/previous/repeat/shuffle zeigen Fehler statt stillschweigend zuversagen

spotify_cli/client.py

@@ -76,7 +76,7 @@ class SpotifyClient:
             data["context_uri"] = context_uri
         if uris:
             data["uris"] = uris
-        if offset:
+        if offset is not None:
             data["offset"] = offset
         if position_ms is not None:
             data["position_ms"] = position_ms
@@ -145,6 +145,19 @@ class SpotifyClient:
     def get_playlists(self, limit=50, offset=0):
         return self._get("/me/playlists", {"limit": limit, "offset": offset})
 
+    def get_all_playlists(self):
+        all_items = []
+        offset = 0
+        limit = 50
+        while True:
+            data = self.get_playlists(limit=limit, offset=offset)
+            items = data.get("items", [])
+            all_items.extend(items)
+            if len(items) < limit:
+                break
+            offset += limit
+        return all_items
+
     def get_playlist(self, playlist_id):
         return self._get(f"/playlists/{playlist_id}")