v0.5.68

• Move the unchanged vendored library and primordials to Node24.21.0; adapt
  Buffer allocation/encoding and transfer ownership, actual timer/context
  accounting, diagnostics links, packed child spawn flags and TTY/TCP
  contracts. Preserve DNS and detached process groups. Default JSON IPC
  works; unavailable V8 binary IPC serialization fails explicitly at use.
  Page readings qualify these contracts; no full Node24 suite score or
  Twenty application startup is claimed.