Make the kubeadm quickstart newcomer-proof

[convee]

What changed

• add make quickstart-doctor for commands, Python, Docker daemon, and fixed ports
• document VM resources, network access, cold-start timing, and the complete cleanup boundary
• make terminal ownership and Chinese/English console login labels explicit
• expose the console follow-up commands on the GitHub Pages quickstart
• add regression coverage for every newcomer handoff

Verified

• third independent anonymous clone at 188e720
• fresh kubeadm VM completed in 232.50s
• example app Running, HTTP 200, public body digest matched
• console modules and 390px layout verified in Chrome
• python3 -m unittest tests.test_helm_package
• make console
• make homepage-check
• make chart-lint
• make chart-render