add function to validate albums

+ extract colors in watchdogg
+ rename color db files

app/api/colors.py

@@ -8,11 +8,9 @@ api = Blueprint("colors", __name__, url_prefix="/colors")
 def get_album_color(albumhash: str):
     album = Store.get_album_by_hash(albumhash)
 
-    if len(album.colors) > 0:
-        return {
-            "color": album.colors[0]
-        }
+    msg = {"color": ""}
 
-    return {
-        "color": ""
-    }
+    if album is None or len(album.colors) == 0:
+        return msg, 404
+
+    return {"color": album.colors[0]}