On Windows the PPID watchdog could never fire: orphans aren't reparented, so
`process.ppid` stays constant after the parent dies (defeating the ppid-change
check), and the standalone bundle pre-bakes `--liftoff-only`, skipping the
relaunch that sets `CODEGRAPH_HOST_PPID` (defeating the host-liveness check).
With neither signal available, an orphaned proxy / direct server ran forever,
the shared daemon never saw the client disconnect, and its idle timer never
armed — node processes accumulated until CPU saturated.
Add a win32-only signal: poll the original parent's liveness directly, since
ppid is stable there. Gated to Windows so POSIX double-fork cases keep relying
on the ppid-change signal (a dead original parent is not proof of orphaning on
POSIX). The decision is extracted into a pure, unit-tested helper shared by all
three watchdog sites (proxy socket, proxy local-handshake, direct mode).
Validated on a real Windows 11 VM: in the exact bundle scenario (direct mode,
no HOST_PPID) an orphaned server now exits within one watchdog poll via the new
path; the POSIX reparent path is unchanged and its integration test still passes.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
