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/site/spec.md

@@ -0,0 +1,52 @@
+# Spec: Site
+
+Directory: `site/`
+
+## Purpose
+
+The ASW framework's own website. Serves as documentation site, demo platform, and living proof that the framework works. Currently built with the Hugo pack.
+
+## Content Types
+
+### Docs (from `../docs/`)
+Framework documentation, mounted as Hugo content via module mount. Not duplicated — sourced from the engine-agnostic `docs/` directory.
+
+### Articles (`content/articles/`)
+Short-form writing about ASW concepts, patterns, and techniques. No TOC.
+
+### Essays (`content/essays/`)
+Long-form writing. TOC, description, wider reading measure.
+
+### Notes (`content/notes/`)
+Exported PKM vault notes. Session logs, diffs, status, tasks, wikilinks.
+
+### Pages (`content/pages/`)
+Static pages: about, etc.
+
+## Engine
+
+Currently Hugo. The site uses `packs/hugo/` as its base and adds:
+- Site-specific layouts and overrides
+- `hugo.toml` with module mounts
+- Site-specific static assets
+
+## Principle
+
+The site is a consumer of the framework, not part of it. A different site could be built with `packs/flask/` or `packs/caddy/` using the same `docs/` and `dist/asw.css`. The framework does not depend on the site. The site depends on the framework.
+
+## Scenarios
+
+### Given a framework docs change
+- **When** a markdown file in `docs/` is modified
+- **Then** the site picks it up automatically via Hugo mount
+- **And** no file in `site/` needs to change
+
+### Given a CSS framework change
+- **When** `src/layers/` is modified
+- **Then** `dist/asw.css` is rebuilt
+- **And** the site serves the updated CSS
+
+### Given a site-only change (new article, essay)
+- **When** content is added to `site/content/`
+- **Then** only the site is affected
+- **And** `src/`, `dist/`, `docs/` are untouched