Extend the RDS feature set with LPS and eRT support, add initial RDS2/logo-transfer wiring, update the control UI and refresh the PlutoSDR example configuration and reference docs.

Add a lock-free stdin PCM ingest path, streaming resampler, stereo-linked limiting and pre-MPX audio filtering, plus the engine/control wiring needed to drive live audio into TX mode. Also document the ingest API and include a helper batch script for piping ffmpeg audio into fmrtx.