initJs

Initializes the Filament WASM module and spreads the Filament namespace onto the global scope so the Karakum-generated externals (which expect top-level globals) can resolve correctly.

onReady fires once the WASM module is fully loaded and the global aliases are in place. All Filament API usage must happen inside (or after) this callback.

Calling this more than once is safe — subsequent calls invoke onReady immediately.