fib-quant 0.1.0-alpha.1

Alpha research release of fib-quant. This release is positioned as an experimental paper-core radial-angular vector quantization implementation with a default-off KV reference feature. It does not claim production KV-cache serving readiness or local reproduction of the FibQuant paper benchmark numbers. Local gates passed: publish preflight, fmt, all-features tests, clippy, examples, docs, cargo package, cargo publish dry-run, and final release assertion.