release: AHP 0.5.0

[connor4312]

Release

Coordinated AHP 0.5.0 release prep across the spec and all five clients.

Release commit SHA for tags:

RELEASE_SHA=e793e92b243dc427eb9bc7c3ebba3237deb552c0

After this PR is merged with a merge commit (not squashed), verify the release SHA is reachable from main, then push the six release tags:

RELEASE_SHA=e793e92b243dc427eb9bc7c3ebba3237deb552c0
git tag spec/v0.5.0        $RELEASE_SHA
git tag rust/v0.5.0        $RELEASE_SHA
git tag kotlin/v0.5.0      $RELEASE_SHA
git tag typescript/v0.5.0  $RELEASE_SHA
git tag v0.5.0             $RELEASE_SHA
git tag clients/go/v0.5.0  $RELEASE_SHA
git push origin \
  spec/v0.5.0 rust/v0.5.0 kotlin/v0.5.0 \
  typescript/v0.5.0 v0.5.0 clients/go/v0.5.0

Kotlin and TypeScript publish via Azure DevOps pipelines, not GitHub Actions:

• clients/kotlin/pipeline.yml
• clients/typescript/pipeline.yml

Those runs appear under the agent-host-protocol pipelines in the vscode-engineering Azure DevOps tenant:
https://dev.azure.com/vscode/VSCode/_build

Validation

• npm test (release commit)
• npm test (post-release 0.5.1 bump)