feat: auto-generated docs sidebar, Decap CMS, content migration infra

Docs restructure:
- Move flat docs into section subdirs (getting-started/, core/,
  components/, reference/) with _index.md for each
- Sidebar auto-generates from content structure — no manual menu entries
- New doc pages appear automatically when created in a section

Decap CMS:
- admin/index.html + config.yml for browser-based editing
- Local mode (npx decap-server) — no OAuth needed
- Collections for all content types: docs, articles, essays, notes, pages

Hugo head.html updated for new CSS layer filenames.
decap-server added as devDependency.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

site/content/docs/core/tokens.md

@@ -0,0 +1,156 @@
+---
+title: "Token System"
+description: "How ASW's CSS custom property hierarchy is structured — Open Props base, semantic aliases, and component tokens."
+type: docs
+weight: 20
+date: 2026-04-09
+tags: ["tokens", "css", "reference"]
+ai-disclosure: "generated"
+ai-model: "claude-sonnet-4-5"
+ai-provider: "Anthropic"
+
+---
+
+## Overview
+
+ASW uses a three-layer token hierarchy built on Open Props. Each layer is additive: base palette → semantic aliases → component-specific values.
+
+```
+Open Props palette   →   ASW semantic aliases   →   component tokens
+--gray-5                  --text-2                    --input-border
+--green-5                 --accent                    --callout-info
+--blue-5                  --link                      --task-done
+```
+
+No layer can break the others. Override a semantic alias, and every component that references it updates.
+
+## Layer 1 — Open Props palette
+
+ASW inlines the Open Props token set directly — no CDN dependency. The full color palette (`--gray-0` through `--gray-15`, plus hue families), spacing scale, font stacks, and easing curves are all available.
+
+```css
+/* These are defined for you — do not redeclare them */
+--gray-0:  oklch(99% 0.005 var(--gray-hue));
+--gray-15: oklch(10% 0.005 var(--gray-hue));
+--green-5: #51cf66;
+--blue-5:  #339af0;
+```
+
+One knob controls the entire gray family:
+
+```css
+:root {
+  --gray-hue: 150; /* default: subtle green tint */
+}
+```
+
+Change `--gray-hue` to `45` for warm stone, `220` for cool blue-gray, `0` for neutral.
+
+## Layer 2 — Semantic aliases
+
+Defined in `:root`, these translate palette values to intent. These are the tokens you override to theme a site.
+
+```css
+:root {
+  /* Surfaces */
+  --surface:   var(--gray-15);   /* page background */
+  --surface-1: var(--gray-14);   /* cards, sidebars */
+  --surface-2: var(--gray-13);   /* hover, raised */
+
+  /* Text */
+  --text:   var(--gray-1);       /* primary */
+  --text-2: var(--gray-3);       /* secondary */
+  --text-3: var(--gray-5);       /* muted */
+
+  /* Accent */
+  --accent:       var(--green-5);
+  --accent-hover: var(--green-4);
+  --on-accent:    var(--gray-15);
+
+  /* Links */
+  --link:       var(--blue-5);
+  --link-hover: var(--blue-4);
+
+  /* Border */
+  --border:        var(--gray-11);
+  --border-subtle: var(--gray-12);
+}
+```
+
+Light mode overrides the same tokens:
+
+```css
+@media (prefers-color-scheme: light) {
+  :root {
+    --surface:   var(--gray-0);
+    --text:      var(--gray-14);
+    --accent:    var(--green-8);
+  }
+}
+```
+
+## Layer 3 — Component tokens
+
+Component tokens are semantic aliases scoped to specific UI patterns. They reference Layer 2 tokens rather than the palette directly.
+
+```css
+/* Agent-native tokens */
+--task-done:    var(--green-5);
+--task-wip:     var(--yellow-5);
+--task-blocked: var(--red-5);
+--task-todo:    var(--gray-5);
+
+--callout-info:  var(--blue-5);
+--callout-warn:  var(--yellow-5);
+--callout-error: var(--red-5);
+--callout-note:  var(--gray-5);
+
+/* Session / vault */
+--session-bg: var(--surface-1);
+--wikilink:   var(--blue-4);
+--redacted:   var(--gray-8);
+```
+
+## Theming a site
+
+To rebrand: override semantic aliases only. Never override the Open Props palette.
+
+```css
+/* your-theme.css — load after agentic.css */
+:root {
+  --gray-hue: 220;            /* cool blue-gray neutrals */
+  --accent:   var(--violet-5);
+  --link:     var(--violet-4);
+}
+```
+
+That is the entire theme file. Surfaces, borders, focus rings, callouts, and task states all update from those three lines.
+
+## Typography scale
+
+```css
+--text-xs:   0.75rem;    /* badges, fine print */
+--text-sm:   0.875rem;   /* metadata, captions */
+--text-base: 1rem;       /* body text */
+--text-2xl:  1.5rem;     /* subheadings */
+--text-3xl:  2rem;       /* section headings */
+
+/* Heading sizes */
+--h1-size: 1.875rem;
+--h2-size: 1.5rem;
+--h3-size: 1.25rem;
+```
+
+## Spacing scale
+
+Aliased from Open Props sizes, with one gap filled:
+
+```css
+--space-1: 0.25rem;   /* var(--size-1) */
+--space-2: 0.50rem;   /* var(--size-2) */
+--space-3: 0.75rem;   /* no OP equivalent — defined by ASW */
+--space-4: 1.00rem;   /* var(--size-3) */
+--space-5: 1.50rem;   /* var(--size-5) */
+--space-6: 2.00rem;   /* var(--size-7) */
+--space-8: 4.00rem;   /* var(--size-9) */
+```