Release Unsga3 0.2.0

[jkbennitt]

Summary

Version cut for Unsga3 0.2.0 (minor). PackageId Unsga3 0.2.0.

What’s in 0.2.0 is the literature work already on main:

• Fix odd-N mating and add an opt-in two-shuffle pool #10 mating: MatingPoolMode.TwoShuffledPasses, TournamentMode.Algorithm2, and the odd-N SBX pairing fix.
• Feasible niching, equal-CV sort, and two-layer reference directions #11 constraints and two-layer references: feasible-only niching / CV fill, equal-CV Deb fix, TwoLayerDasDennis, and OSY / TNK / C1-DTLZ1.

Defaults are unchanged: unconstrained RankNicheDistance, independent mating, and single-layer Das–Dennis. No new IGD or Wilcoxon numbers. No algorithm changes in this PR.

Tag v0.2.0, the GitHub Release, and GitHub Packages publish (publish-github-packages on v*) follow merge. This PR does not tag or publish.

Checklist

• dotnet test Unsga3.slnx -c Release passes locally — 108 passed, 0 failed, 0 skipped (Total 108)
• CHANGELOG.md updated under [0.2.0] — 2026-09-30 (literature entries moved out of Unreleased)
• Public API changes documented (XML docs / README) — already landed in Fix odd-N mating and add an opt-in two-shuffle pool #10 and Feasible niching, equal-CV sort, and two-layer reference directions #11; README status line is 0.2.0
• If survival / normalization / metrics changed: noted oracle impact (or re-ran multi-seed) — no new table in this cut; published 15-seed numbers are not rewritten

Test plan

• dotnet test Unsga3.slnx -c Release — Passed: 108, Failed: 0, Skipped: 0, Total: 108 (SDK 10.0.401)