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/forms/spec.md

@@ -0,0 +1,30 @@
+# Spec: Forms (Layer 04)
+
+File: `src/layers/04-forms.css`
+
+## Purpose
+
+Form element styling. Inputs, selects, textareas, buttons, checkboxes, radios, fieldsets, labels. Accessible by default.
+
+## Scope
+
+### In scope
+- `button`, `input[type="button"]`, `input[type="submit"]`, `input[type="reset"]`
+- `input[type="text|email|password|number|search|url|tel|date|time|datetime-local"]`
+- `select`, `textarea`
+- `fieldset`, `legend`, `label`
+- `input[type="checkbox"]`, `input[type="radio"]`
+- `progress`, `meter`
+- `:focus-visible` ring styling
+- `aria-invalid`, `aria-busy` states
+- `[disabled]` styling
+
+### Out of scope
+- Form layout/grid (→ layouts layer)
+- Custom form components built with data-attributes (→ data-attributes layer)
+
+## Constraints
+
+- References only semantic aliases from `01-tokens.css`
+- All interactive elements must have visible focus indicators
+- Respects `prefers-color-scheme` and `prefers-contrast`