default user volume is 50 now

backend/database/sql/schemas/player_state.sql

@@ -1,6 +1,6 @@
 CREATE TABLE IF NOT EXISTS player_state (
     id INTEGER PRIMARY KEY CHECK(id = 1),
-    volume INTEGER NOT NULL DEFAULT 100,
+    volume INTEGER NOT NULL DEFAULT 50,
     muted BOOLEAN NOT NULL DEFAULT false,
     last_track_path TEXT NOT NULL DEFAULT '',
     last_position_seconds INTEGER NOT NULL DEFAULT 0