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.

Introduce an optional ITU-R BS.412 MPX power limiter, tighten the low-pass/notch filter design around the protected composite path, and document the full DSP architecture and recommended Pluto configuration in detail.

Rework the DSP chain to a clip-filter-clip architecture with cascaded 14 kHz low-pass stages, double 19/57 kHz protection notches, fixed pilot/RDS injection semantics, and explicit MPX gain calibration support. Update config defaults and tests to match the new broadcast-style modulation budgeting and protected composite path.

Keep DSP state persistent across generated frames, move the RDS encoder to arbitrary sample-rate operation, and tune the Pluto profile to the working 2.28 MHz path with the levels that finally decode reliably.

Replace the pilot-derived RDS path with a PiFmRds-style 228 kHz shaped biphase generator, resample it into the composite loop, and retune Pluto example levels plus spectral thresholds around the new RDS behaviour.

Drive RDS in the offline/MPX path from the pilot-locked 57 kHz carrier with biphase symbol timing, and adjust Pluto example levels plus spectral thresholds for the new multiplex behaviour.

Clarify that outputDrive controls only the composite signal path while PlutoSDR hardware gain stays fixed at 0 dB. Relax outputDrive validation to allow stronger composite drive during hardware tuning and update the Pluto example config accordingly.

Introduce CLI TX mode, hardware driver selection, IQ resampling to device rate, and platform-specific PlutoSDR/SoapySDR integrations. Update engine pacing for blocking hardware writes and refresh docs/release notes for the hardware-ready v0.6.0-pre milestone.