Host-mode runner has no Node.js so JS composite actions fail.
All steps are now plain shell — git clone for checkout, docker
CLI for build/push. Zero external action dependencies.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
The previous workflow ran jobs inside node:20-bookworm which has no
Docker CLI. Re-mapped label to :host and replaced composite actions
with direct docker build/push shell commands.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
