Add Amore release GitHub Action

[mfauzaan]

Summary

• add a GitHub Actions release workflow using AmoreComputer/release-action
• resolve release version/build from Version.xcconfig and release notes from CHANGELOG.md
• publish stable tag runs to GitHub Releases with the generated DMG asset
• document tag-based release flow and required Action secrets

Notes

• The upstream Amore action README documents @v1, but that tag does not exist yet, so the workflow pins the current action commit SHA.

Validation

• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/release.yml"); puts "release.yml ok"'\n- GO111MODULE=on go run github.com/rhysd/actionlint/cmd/actionlint@latest .github/workflows/release.yml .github/workflows/swift-tests.yml\n- git diff --check -- .github/workflows/release.yml README.md\n- local metadata extraction dry run against Version.xcconfig and CHANGELOG.md