Release 10.2.0: date the changelogs, tag v10.2.0, close the 10.x-only issues, carry the sections to main #365

Change

The release steps after every in-scope PR of #358 has merged into release/10.x, as #301 and #328 did for 10.1.0. #331 only opens the version.

1. Check before the tag. All of these hold on the release commit, with every fix merged, so the fixes are checked together and not only one PR at a time:
   • Every CI lane is green: PostgreSQL 16 and 18, on the EF Core floor and the newest-patch legs, and both smoke-test modes. These stay the gates.
   • dotnet run tools/oracles.cs seeds re-proves locally that every seed is caught (AGENTS.md, workflow step 4).
   • NullElementTests passes on both EF legs. The six composition sweeps that hold Contains(element) on a range or RangeSet is NULL in SQL for a NULL element: the negation drops the row EF Core keeps, and a projection into bool throws #381 and The range factories over a NULL element build a range: CreateFinite gives empty and CreateUnboundedStart/End give (,), where EF Core answers NULL #382 are on main only, so on this line it holds 10.x: Contains(element) on a range or RangeSet is NULL in SQL for a NULL element (port of #381) #387 and 10.x: the range factories over a NULL element build a range instead of answering NULL (port of #382) #388: the negation, the bool projection, All, and a range factory over a NULL element consumed by Contains, Overlaps, == null and IsEmpty().
   • The translation-support inventory (Translation-support inventory: every public query member classified as server, client-only or planned, and probed against EF Core #384, PR test: translation-support inventory — every public query member classified and probed against EF Core (#384) #386) is evaluated, and each finding is triaged. Done 2026-10-25 (evaluation on #384). It ran on EF Core 10.0.0 and 10.0.13 with the same result as on main. Its only defect is RangeLowerBoundComparer.Compare runs as SQL in the range order: EF Core rewrites any Compare(a, b) to the natural comparison #385, which is deferred and documented (10.x: docs: name the two known differences 10.2.0 ships with — value set Union/Remove over NULL (#360) and RangeLowerBoundComparer in a query (#385) #397). The undocumented members are docs only (docs: what-runs-where omits Equals, RangeSet.Count, the indexers, Values, Parse/ToString and the NodaTime conversions (found by #384) #399, in 10.2.0: PR docs: list every public query member in what-runs-where (#399) #400 on main, PR docs: list every public query member in what-runs-where (10.x, #399) #401 on 10.x).
   • No further discovery round runs before the tag. A new round needs a named mechanism or contract that no sweep covers yet; "there may be another bug" doesn't move the release (Epic: 10.2.0 #358, "Release boundary").
2. Date the five changelogs. Set ## [10.2.0] — yyyy-mm-dd in all five, in the commit that gets tagged; no test or workflow checks the date.
3. Tag v10.2.0 (annotated, as v10.1.0) on that commit. The release workflow publishes, and the nuget environment approval is the maintainer's.
4. Close the 10.x-only issues by hand with the merge commit, since Closes #n acts only on main: 10.x: LowerBound() and UpperBound() in a query: == null becomes WHERE FALSE and ?? loses its COALESCE (port of #349) #354, 10.x: a predicate over a null range, RangeSet or value set is false in memory and in SQL (port of the predicate half of #350, #355 and #356) #357, 10.x: RangeIntersectAgg returns empty over a sequence holding a null range, where range_intersect_agg skips the NULL; RangeAgg throws (port of #361) #363, 10.x: docs: ordering by LowerBound() or UpperBound() puts open-ended and empty rows where PostgreSQL puts NULLs (port of #359) #364, 10.x: the empty-root rewrite casts EF Core's _ord column to the range type on EF Core 10.0.2 and later (port of #319) #325, 10.x: Contains(element) on a range or RangeSet is NULL in SQL for a NULL element (port of #381) #387, 10.x: the range factories over a NULL element build a range instead of answering NULL (port of #382) #388, 10.x: docs: name the two known differences 10.2.0 ships with — value set Union/Remove over NULL (#360) and RangeLowerBoundComparer in a query (#385) #397. docs: what-runs-where omits Equals, RangeSet.Count, the indexers, Values, Parse/ToString and the NodaTime conversions (found by #384) #399 and docs: the in-memory reasons overstate what PostgreSQL lacks, and the Shift/Expand one is stale since #224 #402 are closed from main by PR docs: list every public query member in what-runs-where (#399) #400 and PR docs: give each in-memory operation its real reason (#402) #403; check that their 10.x halves, PR docs: list every public query member in what-runs-where (10.x, #399) #401 and PR docs: give each in-memory operation its real reason (10.x, #402) #404, have merged too. Most are closed when their PR merges; this step checks that none is left open.
5. Carry 10.2.0 to main in one PR, as chore: carry the 10.1.0 release to main #330 did for 10.1.0:
   • the [10.2.0] sections into main's five changelogs, verbatim;
   • ## Changed answers in 10.2.0 into docs/migration.md. 10.x: LowerBound() and UpperBound() in a query: == null becomes WHERE FALSE and ?? loses its COALESCE (port of #349) #354's subsection there meets the same heading under ## Migration from v10.x; keep one and link it from the other;
   • whatever the conventions then require on main. For 10.1.0 that was PackageValidationBaselineVersion and main's SECURITY.md row.

Done when

v10.2.0 is on nuget.org for all four packages, GitHub's Latest release stays the highest stable version, the 10.x-only issues are closed, and main carries the 10.2.0 sections.