Clone mode used to read the same WAV twice (speaker encoder then codec
encoder), which failed silently on Windows where pipeline_codec_encode
returned empty on the second pass. PipelineTTSSynthesizeParams now takes
ref_audio_24k + ref_n_samples instead of a path. The CLI calls
audio_read_mono once, holds the buffer in a unique_ptr until synthesis
returns, and feeds the same pointer to both encoders.