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/notes/wikilinks.md

@@ -0,0 +1,26 @@
+---
+title: "Wikilinks"
+description: "Internal knowledge-graph links styled as dotted underlines."
+section: notes
+prev-url: "tasks/"
+prev-title: "Tasks"
+next-url: "status/"
+next-title: "Status"
+type: notes
+date: 2026-04-09
+tags: ["notes", "wikilinks", "reference"]
+ai-disclosure: "generated"
+ai-model: "claude-sonnet-4-5"
+ai-provider: "Anthropic"
+
+---
+
+## Overview
+
+Use `data-wikilink` on anchor tags to mark links as internal knowledge-graph references.
+
+```html
+<a href="/notes/tasks/" data-wikilink>Tasks</a>
+```
+
+Renders with a dotted underline distinguishing it from a regular hyperlink.