Vendored PolarQuant core

Two files vendored verbatim from caiovicentino/eoq-quantization @ commit 15a12160245d7d3015290c6c5b6dbb7f22094d5e:

• polar_quant.py — the actual PolarQuant algorithm (per-block normalize → Walsh-Hadamard rotation → Lloyd-Max quantizer matched to N(0,1) → optional 1-bit QJL residual correction).
• utils.py — QuantizedTensor, quantize_absmax, dequantize, and the entropy-estimation helper. polar_quant.py only depends on utils from inside the compare_polar_vs_absmax helper, so the rest of the pipeline works without it; we still vendor utils.py so that helper stays usable.

Paper: PolarQuant: Optimal Gaussian Weight Quantization via Hadamard Rotation for LLM Compression, Caio Vicentino, arXiv:2603.29078 (March 2026).

See LICENSE.md for the upstream license situation (currently: no license file in the upstream repo; vendored under the constraints documented there).

The integration glue that calls into these modules from a HuggingFace checkpoint lives one directory up in polarquant_apply.py; do not modify the vendored files in place — patch upstream and re-vendor instead.