Document the new batch_stream_generate_voice_clone() method including
a usage example showing voice prompt broadcasting, per-item chunk
accumulation, and WAV output. Add entry to the "Added in this fork" list.
Allow users to set any overlap_samples value including 0 to disable
crossfade blending entirely. Renamed MIN_BLEND_SAMPLES to
DEFAULT_BLEND_SAMPLES and removed the enforced minimum.
- Replace linear crossfade with Hann window for smoother transitions
- Add MIN_BLEND_SAMPLES (512) as floor for blend region
- Add Hann fade-in on first chunk to prevent startup pop
- Add Hann fade-out on final chunk to prevent ending pop
- Trim chunk tails before emission to prevent echo artifacts
- Update README with audio quality fixes documentation