* refactor(platform): give the host platform one owner and ratchet ambient process.platform reads
* refactor(process): pass the host platform to process sampling instead of reading it ambiently
#10755 added two process.platform reads (ps selection in process sampling and the
desktop build doctor's ps fact) after the host-platform ratchet was measured.
The desktop fact already receives the host platform from doctor; process sampling
now receives it from the capture harness, removing all five ambient reads there.