Update CI and release workflows

[austin-smith]

What Changed

• Updated the GitHub Actions and Docker workflow action major versions.
• Removed Docker metadata and login conditions that cannot run in the tag-only publish workflow.
• Corrected the standalone release bundle layout and changed the archive to .tar.gz so pnpm runtime links are preserved.
• Updated the documented release entrypoint and pnpm version.

Why

The workflows were using older action releases, and the existing ZIP bundle was not runnable after extraction because its layout was incorrect and pnpm's symbolic links were flattened.

Validation

• pnpm lint
• pnpm test — 74 tests passed
• pnpm build
• actionlint
• Extracted release archive smoke test: homepage, public asset, and Next.js static asset returned HTTP 200
• git diff --check