refactor(ci): flatten workflow directory structure to top-level naming

[jimisola]

Summary

GitHub Actions does not support subdirectory paths for cross-repository reusable workflow references (actions/runner#2102). This causes the error:

invalid value workflow reference: workflows must be defined at the top level of the .github/workflows/ directory

Rename all 20 reusable workflows from subdirectories to prefixed top-level names and update all internal references.

Renamed files

Old path	New path
common/check-release.yml	common-check-release.yml
common/publish-to-docker.yml	common-publish-to-docker.yml
common/publish-to-github-pages.yml	common-publish-to-github-pages.yml
common/release-preview.yml	common-release-preview.yml
common/release.yml	common-release.yml
java/build-gradle.yml	java-build-gradle.yml
java/build-maven.yml	java-build-maven.yml
java/lint.yml	java-lint.yml
java/publish-to-gradle.yml	java-publish-to-gradle.yml
java/publish-to-maven.yml	java-publish-to-maven.yml
python/build-hatch.yml	python-build-hatch.yml
python/build-poetry.yml	python-build-poetry.yml
python/lint.yml	python-lint.yml
python/publish-to-python-test.yml	python-publish-to-python-test.yml
python/publish-to-python.yml	python-publish-to-python.yml
typescript/build.yml	typescript-build.yml
typescript/lint.yml	typescript-lint.yml
typescript/publish-to-npm.yml	typescript-publish-to-npm.yml
typescript/publish-to-vscode.yml	typescript-publish-to-vscode.yml

Test plan

• Merge this PR first, then merge the consumer repo PR (reqstool-vscode)
• Trigger a manual build in a consumer repo and verify workflows resolve correctly