openhop-dev/openhop_core#123 settled on fabric.origin_tx: default | all
as the name for sending locally originated packets out on every radio,
and openhop-dev/openhop_core#124 with openhop-dev/openhop_repeater#412
implement that knob in core. Use the same key here so a Fabric config
means one thing whichever implementation lands.
local_tx_mode is still read, so a config written against the first
version of this branch keeps its behaviour. If both keys are set to
different modes, startup rejects the config before any hardware is
opened, since there is no way to tell which one the operator meant.
While running, the engine reads the option through the same helper and
lets origin_tx win. Validation errors name the key the operator actually
wrote.
The radio stack meta and the startup log report origin_tx.