frontendDelayTest dereferences a null stream; limePPSDO always exits successfully #406

frontendDelayTest passes trx.get() straight into MeasureChannelDelays, which calls Start() and dispatches worker threads on it; StreamCreate returns null when the stream port is unavailable or the config is rejected.

limePPSDO captures the OpStatus of resetPPSDO / enablePPSDO / runMonitoring / disablePPSDO in runStatus and uses it only to skip the following commands; main then unconditionally executes return EXIT_SUCCESS, so a failed register operation prints an error to stderr and still reports success to the shell.