Release Unsga3 0.2.1

[jkbennitt]

Summary

Version cut for Unsga3 0.2.1 (patch). PackageId Unsga3 0.2.1.

What’s in 0.2.1 is already on main after the 0.2 finish (PR #14, 56541980):

• Multi-target net8.0 and net10.0 for the library, tests, and BasicUsage. tools/OracleCompare stays net10.0.
• PerformanceIndicators.GenerationalDistancePlus (Ishibuchi GD+), with hand-case unit tests. No new benchmark IGD table.
• DocFX API reference (dotnet tool restore && dotnet docfx docfx.json; CI job api-docs).
• docs/WILCOXON-RESULTS.md is the matched DTLZ2 re-run (n_var=12 on C# and pymoo). ZDT2 stays out of that table. No new ZDT2 Wilcoxon numbers.
• Measured 15-seed tables for OSY, TNK, C1-DTLZ1, and mating opt-ins in docs/NEW-SURFACES-RESULTS.md (landed after 0.2.0).

Defaults stay unconstrained RankNicheDistance, independent mating, and single-layer Das–Dennis. This PR does not change the algorithm. nuget.org is not added. GitHub Packages stays the only publish target, on v* tags, as in publish-github-packages.

Left under [Unreleased] (same as the 0.2.0 cut): the optional TypeSafe pass, and the generic initialPopulation docs wording.

Version sources: Directory.Build.props <Version>, CITATION.cff, README status line, bug-report placeholder. No Version / PackageVersion overrides in the csproj files.

Tag after merge

v0.2.0 is a lightweight tag on the 0.2.0 merge commit. After this PR merges, tag v0.2.1 the same way on the merge commit. publish-github-packages runs on v* and pushes to GitHub Packages. This PR does not create the tag.

git fetch origin main
git tag v0.2.1 origin/main
git push origin v0.2.1

Checklist

• dotnet test Unsga3.slnx -c Release passes locally — 110 passed, 0 failed, 0 skipped on net8.0 and the same 110 on net10.0
• CHANGELOG.md updated under [0.2.1] — 2026-10-01 (0.2-finish notes moved out of Unreleased)
• Public API changes documented (XML docs / README) — already landed in Measure constrained problems and mating opt-ins #13 and Refresh matched DTLZ2 Wilcoxon and land the 0.2 surface #14; README status line is 0.2.1
• If survival / normalization / metrics changed: noted oracle impact (or re-ran multi-seed) — no new table in this cut; published Wilcoxon numbers are not rewritten

Test plan

• dotnet test Unsga3.slnx -c Release — Passed: 110 per target framework (net8.0 and net10.0), Failed: 0, Skipped: 0 (SDKs 10.0.401 and 8.0.425).
• Local pack check (not published): Unsga3.0.2.1.nupkg, id Unsga3, version 0.2.1, target frameworks net8.0 and net10.0.