fix(antigravity): stop health checks from filling the disk with _MEI folders (#12008)

The health probe launched the PyInstaller ACP binary every minute and force killed it, leaving about 1 GB of _MEI files per run. The probe now resolves the install on disk without spawning. Each ACP process gets its own temp directory under the profile that is removed when the runtime closes, and the driver sweeps the profile temp root on create.

Continues #11657 by Vita Skacel. Owned temp directory approach from #9626 by ariszz.

Co-authored-by: Vita Skacel <skacel.vita@gmail.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>