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/specs/framework/typography/spec.md

@@ -0,0 +1,30 @@
+# Spec: Typography (Layer 02)
+
+File: `src/layers/02-typography.css`
+
+## Purpose
+
+Prose and heading defaults. Responsive typography scale, font stacks, line heights, heading hierarchy, inline elements (code, mark, links, abbreviations).
+
+## Scope
+
+### In scope
+- `body` font defaults
+- `h1`–`h6` sizing and weight hierarchy
+- `p`, `blockquote`, `ul`, `ol`, `li` prose rhythm
+- `a` link styling
+- `code`, `kbd`, `pre` inline/block code
+- `mark`, `abbr`, `small`, `sub`, `sup` inline semantics
+- `hr` horizontal rules
+- Responsive font-size scaling
+
+### Out of scope
+- Syntax highlighting colors (→ chroma layer)
+- Navigation typography (→ navigation layer)
+- Component-specific text styling (→ components layer)
+
+## Constraints
+
+- References only semantic aliases from `01-tokens.css`
+- No Open Props primitives directly
+- No element selectors that belong to landmarks (nav, footer, header)