Per Pico CSS landmark pattern and HTML5 spec:
- Site <header> with <nav> moved to baseof.html
- Site <footer> moved to baseof.html
- All section layouts (single, list, docs, paper, vault, index)
now only define <main> content — no duplicate nav/footer
- Article <header> stays inside <article> (different semantic role)
- layouts/docs/single.html: docs section layout with sidebar nav + TOC
- layouts/paper/single.html: essay layout with byline, abstract, tags
- layouts/vault/single.html: vault layout with sidebar nav + front-matter prev/next
- content/papers/on-semantic-html.md: 'On Semantic HTML as Agent Interface'
- content/papers/on-sessional-continuity.md: 'On Sessional Continuity'
All layouts use partial nav.html for dynamic menus. Paper layout
uses data-paper, data-abstract, data-byline, data-role=tag-cloud.
36 pages build clean, paper pages live at /papers/.
Closes: asw#14, asw#10
