feat: add OpenSpec specs and changes for ASW restructure

Specs: repo-structure, 10 framework layer specs, packs, site.
Changes: repo-restructure (10 tasks), css-refactor (12 tasks),
legacy-import (proposal + triage categories).

Supersede docs/css-refactor-plan.md in favor of OpenSpec change.

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

openspec/changes/css-refactor/proposal.md

@@ -0,0 +1,60 @@
+# Proposal: CSS Layer Refactor
+
+## Intent
+
+Restructure CSS layers to clean architecture: alias all Open Props primitives through `01-tokens.css`, split the monolithic `03-components.css` into purpose-specific files, redistribute misplaced content, and rename files to match their actual responsibilities.
+
+**Goal: each CSS file has a single clear purpose, and no file references Open Props primitives directly.**
+
+This plan was originally documented in `docs/css-refactor-plan.md` and is imported here as an OpenSpec change for tracking and execution.
+
+## Scope
+
+### In Scope
+- Add missing semantic aliases to token file (~10 new aliases)
+- Extract editorial rules out of token file into their proper layers
+- Rename `01-asw.css` → `01-tokens.css` (pure tokens, no rules)
+- Fix all Open Props primitive leaks across all layers
+- Split `03-components.css` into: `03-landmarks.css`, `04-forms.css`, slimmed `05-components.css`, `06-navigation.css`
+- Rename all files to final numbering scheme
+- Merge `08a-essay.css` into layout layer
+- Audit and remove unused tokens
+
+### Out of Scope
+- New CSS features or components
+- Layout changes
+- Content changes
+- Repo restructure (separate change, happens first)
+
+### Current → Target Layer Map
+
+```
+CURRENT                          TARGET
+═══════                          ══════
+00-reset.css                     00-reset.css (unchanged)
+01-asw.css                  ──▶  01-tokens.css (pure :root, no rules)
+02-semantic.css             ──▶  02-typography.css
+03-components.css           ──▶  03-landmarks.css (nav, article, footer, hgroup)
+                            ──▶  04-forms.css (inputs, buttons, selects)
+                            ──▶  05-components.css (dialog, accordion, breadcrumb)
+                            ──▶  06-navigation.css (sidebar, TOC)
+04-data-attrs.css           ──▶  07-data-attrs.css
+05-utilities.css            ──▶  08-utilities.css
+06-charts.css               ──▶  09-charts.css
+07-chroma.css               ──▶  10-chroma.css
+08-layout.css + 08a-essay   ──▶  11-layout.css (merged)
+09-landing.css              ──▶  12-landing.css
+```
+
+## Approach
+
+One atomic step per session. Build check after every step. No step touches more than two files. Full plan in `docs/css-refactor-plan.md`.
+
+## Prerequisites
+
+- **Depends on:** `repo-restructure` (files must be in `src/layers/` first)
+
+## Risks
+
+- **Visual regression** — mitigated by build + visual check after each step
+- **Specificity changes** — layer reordering could affect cascade. Mitigated by keeping relative order.