feat: TurboQuant enhancements — layer-adaptive, beta codebook, temporal decay

[MaTriXy]

Summary

• Layer-adaptive compressor — per-layer bit-width config. Last 20% of layers get 8-bit, first 80% get 3-bit. Mode 2: PPL +0.14% at 3.5x compression.
• Beta distribution codebook — Lloyd's on true Beta(d/2, d/2) for d<256. Tighter MSE distortion.
• Temporal decay compressor — age-based bit allocation with layer-aware thresholds. Python logic complete.

Files changed

• turboquant/layer_adaptive.py — LayerAdaptiveCompressor (new)
• turboquant/temporal_decay.py — TemporalDecayCompressor (new)
• turboquant/codebook.py — added _lloyds_beta(), use_beta param
• turboquant/__init__.py — new exports
• tests/test_layer_adaptive.py — 16 tests (new)
• tests/test_codebook_beta.py — 22 tests (new)
• tests/test_temporal_decay.py — 22 tests (new)
• docs/turboquant-enhancements.md — documentation (new)

Test plan

• 201 tests pass (141 original + 60 new)
• Benchmark beta codebook MSE vs gaussian for d=64, 128, 256
• Validate temporal decay bit selection across layer/age combos

[TheTom]

hey there. thank you for the contribution. i'll be getting to them. I apologize for the delay.