Function die_with_parent_supported 

pub const fn die_with_parent_supported() -> bool

Whether ClaudeBuilder::die_with_parent does anything on this platform.

true only on Linux, which is the only target with a kernel-level parent-death signal (PR_SET_PDEATHSIG). Elsewhere the option is accepted and has no effect, so a supervisor that needs the guarantee everywhere must check this and run its own watchdog rather than assume coverage it does not have.