Separate prebuilt runtime image packages

[shibayan]

Summary

• publish language runtime images to dedicated *-base GHCR packages
• update all templates, smoke tests, and release validation to use the new package names
• verify that published base images are anonymously accessible
• document package visibility and backward-compatibility requirements
• increment template patch versions

Why

Dev Container Template artifacts and prebuilt runtime images were published under the same GHCR package names. Separating the runtime images prevents unrelated OCI artifact types from sharing one package and keeps package responsibilities clear.

Existing runtime tags are intentionally retained because previously released template versions still reference them.

Impact

After the first workflow push, each new *-base package must be made public in GitHub Packages. The workflow then verifies anonymous access before succeeding.

Validation

• parsed every devcontainer-template.json
• checked staged changes with git diff --check
• confirmed no active legacy runtime-image references remain in workflows or templates
• reviewed the complete staged diff

[Copilot]

Pull request overview

This PR separates prebuilt language runtime images from template artifacts by publishing runtime images to dedicated *-base GHCR packages, then updates templates and CI validation to consistently reference the new package names while retaining legacy tags for backward compatibility.

Changes:

• Updated all Azure Functions templates’ runtime FROM images to use *-base packages and bumped template patch versions.
• Updated release validation and smoke tests to verify/pull the new *-base runtime images.
• Added prebuild documentation and a workflow job to fail fast if new *-base packages aren’t made public (and verifies anonymous access).

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/azure-functions-python/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-python/.devcontainer/Dockerfile	Switch base image to azure-functions-python-base.
src/azure-functions-powershell/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-powershell/.devcontainer/Dockerfile	Switch base image to azure-functions-powershell-base.
src/azure-functions-node/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-node/.devcontainer/Dockerfile	Switch base image to azure-functions-node-base.
src/azure-functions-java/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-java/.devcontainer/Dockerfile	Switch base image to azure-functions-java-base.
src/azure-functions-go/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-go/.devcontainer/Dockerfile	Switch base image to azure-functions-go-base.
src/azure-functions-dotnet/devcontainer-template.json	Patch bump to reflect runtime image package rename.
src/azure-functions-dotnet/.devcontainer/Dockerfile	Switch base image to azure-functions-dotnet-base.
README.md	Document that runtime images are now separate *-base packages.
prebuild/README.md	New documentation for runtime image publishing/visibility expectations.
.github/workflows/release.yml	Update release validation to inspect *-base images.
.github/workflows/prebuild.yml	Publish *-base images and add anonymous-access verification gate.
.github/actions/smoke-test/build.sh	Update smoke test prebuild image reference to *-base.

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