refactor: rename content types to semantic taxonomy

- vault → notes (PKM-exported content)
- posts → articles (short-form, no TOC)
- papers → essays (long-form, with TOC)
- type: post → type: article (posts are just short articles)
- layouts/paper → layouts/essay
- 08a-paper.css → 08a-essay.css
- CSS: fix redundant li resets, remove role="main" from article,
  replace <small> prev/next labels, add console layout
- Update hugo.toml menus, internal URLs, front matter throughout
- Add docs/context.md, docs/css-refactor-plan.md

content/_index.md

@@ -15,9 +15,9 @@ Built for sites generated by agents and read by agents. Navigable by humans.
 ## What this is
 
 - [Docs](/docs/) — the ASW HTML vocabulary, layout system, and components
-- [Vault](/vault/) — live ASW notation: task lists, sessions, diffs, wikilinks
-- [Posts](/posts/) — writing and vocabulary reference
-- [Papers](/papers/) — longer-form thinking on the semantic web
+- [Vault](/notes/) — live ASW notation: task lists, sessions, diffs, wikilinks
+- [Posts](/articles/) — writing and vocabulary reference
+- [Papers](/essays/) — longer-form thinking on the semantic web
 
 ## The design principle
 
@@ -26,7 +26,7 @@ No invented CSS classes. Every style target is either a semantic HTML element or
 ```html
 <aside data-callout="note">This is a note.</aside>
 <section data-layout="grid">...</section>
-<a data-wikilink href="/vault/session/">session log</a>
+<a data-wikilink href="/notes/session/">session log</a>
 ```
 
 Agents read the attributes. Humans read the content. The CSS connects them.
@@ -38,5 +38,5 @@ This is a **note callout** rendered via the `callout` shortcode. Output: `<aside
 {{< /callout >}}
 
 {{< callout tip >}}
-See the [Getting Started](/posts/getting-started/) post to wire ASW into your Hugo project.
+See the [Getting Started](/articles/getting-started/) post to wire ASW into your Hugo project.
 {{< /callout >}}