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

layouts/partials/head.html

@@ -17,9 +17,24 @@
 {{- partial "meta/ai-disclosure.html" . -}}
 {{- partial "meta/json-ld.html"       . -}}
 
-{{- /* ── CSS — fingerprinted via Hugo Pipes ─────────────────────── */}}
-{{ $css := resources.Get "css/asw-built.css" | minify | fingerprint }}
-<link rel="stylesheet" href="{{ $css.RelPermalink }}">
+{{- /* ── CSS ────────────────────────────────────────────────────── */}}
+{{- if hugo.IsDevelopment }}
+  <link rel="stylesheet" href="/vendor/open-props.min.css">
+  <link rel="stylesheet" href="/vendor/media.min.css">
+  <link rel="stylesheet" href="/css/layers/00-reset.css">
+  <link rel="stylesheet" href="/css/layers/01-asw.css">
+  <link rel="stylesheet" href="/css/layers/02-semantic.css">
+  <link rel="stylesheet" href="/css/layers/03-components.css">
+  <link rel="stylesheet" href="/css/layers/04-data-attrs.css">
+  <link rel="stylesheet" href="/css/layers/05-utilities.css">
+  <link rel="stylesheet" href="/css/layers/06-charts.css">
+  <link rel="stylesheet" href="/css/layers/07-chroma.css">
+  <link rel="stylesheet" href="/css/layers/08-layout.css">
+  <link rel="stylesheet" href="/css/layers/08a-paper.css">
+  <link rel="stylesheet" href="/css/layers/09-landing.css">
+{{- else }}
+  <link rel="stylesheet" href="/asw.css">
+{{- end }}
 
 {{- range .AlternativeOutputFormats -}}
 <link rel="{{ .Rel }}" type="{{ .MediaType.Type }}" href="{{ .Permalink | safeURL }}">