When the server (soundboard_sounds table) returns no pads, the client now
loads them from a JSON5 config file (loadGamedata accepts plain JSON and
JSON5). Useful when the DB / CMS isn't set up yet.
File-defined pads play locally for the clicker; DB-backed pads still go
through the server broadcast so everyone in the room hears them. Ships a
radio-style soundboard-sounds.json5.example template.