v0.1.0

• Initial release: SignalScope (listen(), run(), context(),
  signal(), restore()) cancels a rasuvaeff/context context on
  SIGTERM/SIGINT through requestCancel(); a second signal restores and
  hands itself to the previous disposition. SignalReceived is the reason.
  restore() cancels the scoped context (like Go's NotifyContext stop), so
  a scope per job never stays attached to a long-lived parent.