Class IfcApiModelPassthroughFactory

Cooperative twin of from() (used by OpenModelAsync): the data parse runs with periodic event-loop yields so progress UI can repaint (issue #301 §2) for IFC and AP214/AP203/AP242 alike. IFC geometry extraction is cooperative too; AP214's stays synchronous (thunk-tree extraction has no flat product loop yet) and reports as a heartbeat.

Streamed-open twin of fromAsync (used by OpenModelStreamed): IFC models parse through the streaming columnar indexer (no per-record object phase — see IfcApiProxyIfc.createStreamed); everything else behaves like fromAsync. Non-IFC formats and any streamed-open failure fall back to the classic cooperative path, so this never does worse than fromAsync — the safety net behind embedder feature flags.