fix: fall back to POSIX ps flags on BusyBox/Alpine

[Luc0-0]

ps -lx is procps-specific and doesn't work on BusyBox (Alpine Linux). BusyBox either ignores the flags and prints its own format, or returns empty output — both cause downstream parsing issues in @webpod/ingrid.

This adds a psFallback lookup using ps -eo pid,ppid,args (POSIX-compliant, works on BusyBox). If the primary ps -lx returns no results, it automatically retries with the fallback.

Related: google/zx#1369, webpod/ingrid#11

[antongolub]

Can we somehow pick the proper flow here? Additional condition?
const lookupFlow = IS_WIN ? IS_WIN2025_PLUS ? 'pwsh' : 'wmic' : 'ps'?

[Luc0-0]

Can we somehow pick the proper flow here? Additional condition? const lookupFlow = IS_WIN ? IS_WIN2025_PLUS ? 'pwsh' : 'wmic' : 'ps'?

yeah, added IS_BUSYBOX using fs.existsSync('/bin/busybox') — same pattern as IS_WIN/IS_WIN2025_PLUS, picks psFallback directly instead of retrying. no runtime overhead, just a sync file check at startup.

[antongolub]

Thanks for raising this — the BusyBox/Alpine issue is real. However, the fix required a broader set of related changes (switching to POSIX ps -eo pid,ppid,args for all Unix, adjusting the output parser, adding CI coverage for Alpine/macOS/multi-node), so we've taken this on ourselves. Appreciate the report!