[Blind-Striker]

Release preparation for 3.0.0 of both packages (stack #69 is merged into master).

This PR

• CHANGELOG.md: [Unreleased] becomes [v3.0.0] (linked to the v3.0.0 release tag, like earlier entries); the "not yet published" line is replaced by the two package versions.

• Living docs drop "unreleased" from the 3.0.0 descriptions: client runtime, Extensions and composition, platform and packaging, maintenance playbook (date lines set to 2026-10-24). Directory.Build.props is already 3.0.0 for both packages.

• CHANGELOG.md and the three README copies: the AWS package pins 3.0.0 needs. AWSSDK.Extensions.NETCore.Setup 4.0.102.4 needs AWSSDK.Core 4.0.102.11, so a project that pins lower versions gets NU1605 on restore.

Dogfood (CI-built 3.0.0-nightly.20261023.49573c2 from GitHub Packages, local win-x64)

Upgraded by changing only Directory.Packages.props and nuget.config; no consumer code changed.

Consumer	Result
badge-smith (2.0.0/2.0.1 → nightly, net10)	Build 0 warnings; Api.Tests 629/629 and CDK.Tests 4/4 on both base and nightly.
dotnet-aspire-for-localstack (net8/net9/net10)	net8/net9 resolve netstandard2.0, net10 resolves net10.0. Unit tests 486/486 on both base and nightly (built with NuGetAudit=false, because the base already fails on existing NU1901/NU1902 audit errors). Integration tests on nightly: 17/22. The same 5 Lambda playground tests also fail on base: the Aspire Lambda emulator cannot find its WrapperLocalStack.Lambda.*.exe.
dotnet-otel-aspire-localstack-demo (net10)	Builds with no new warnings once the central AWSSDK.Core pin is raised to 4.0.102.11. Its only test project contains no tests.

The only upgrade friction found: consumers that pin AWSSDK.Core (4.0.9.6, 4.0.100.3) or Setup (4.0.4.10) centrally hit NU1605 until they raise the pins. Documented in this PR.

Merge timing

Merge this immediately before publishing, so master does not describe 3.0.0 as released while the feed still lacks it. Then:

1. Run Manual Package Publishing for LocalStack.Client 3.0.0 → nuget. Wait until nuget.org indexes it.
2. Run the same workflow for LocalStack.Client.Extensions 3.0.0 with client version 3.0.0 → nuget.
3. Check both feeds, then create tag v3.0.0 and the GitHub release from this changelog section.

Docs-only change; no runtime tests run for this PR.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None