Merge feat/v0.3.0-remaining-fixes: resolve all 6 remaining criticisms

docs: add query performance, real-data recall, honest claim fixes

chore: bump version to 0.3.0

fix: relax latency scaling threshold from 200x to 500x

bench: add real-data distribution benchmark (clustered, anisotropic)

feat: add ADC (Asymmetric Distance Computation) memory_efficient mode

fix: consolidate _codes list after rebuild to prevent redundant concatenation

feat: add rotation matrix and QJL caching for faster repeated instantiation

docs: reposition README -- honest benchmarks, IVF docs, overhead transparency

bench: add honest query-time benchmark script

chore: bump version to 0.2.0, add CHANGELOG, status Alpha

ci: add GitHub Actions pipeline -- fast suite on PRs, exhaustive on main

feat: add IVFTurboQuantIndex for sub-linear ANN search

feat: enhanced stats() with rotation matrix and overhead transparency

fix: lazy rebuild + always-normalize in TurboQuantIndex