Add PQSetup documentation site

[galjos]

Summary

• make the README follow PQEnalyzer’s compact technical format
• combine PQViewer’s documentation structure with ThermoScreening’s Sphinx and Furo stack
• add real MOF-5 workflow screenshots and GitHub Pages deployment from main
• document setup, validation boundaries, run packages, CLI, and compatibility

Checks

• python -m pytest — 180 passed, 12 skipped
• npm --prefix frontend test — 29 passed
• npm --prefix frontend run build
• strict Sphinx HTML and link checks
• desktop and mobile page, search, theme, image, and overflow checks