refactor: CSS tasks 1-6 — add token aliases, fix all primitive leaks

- Rename 01-asw.css → 01-tokens.css (pure :root, no rules)
- Add semantic aliases: --weight-*, --shadow-*, --focus-ring-width,
  --dropdown-min-width, --space-5a, --weight-light, --border-width-thick
- Extract editorial rules from token file to components/layout
- Replace all Open Props primitives in layers 02-09 with semantic aliases
- Zero primitive leaks remain outside 01-tokens.css

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

src/main.css

@@ -12,7 +12,7 @@
 
 /* 2. Framework layers */
 @import "./layers/00-reset.css";
-@import "./layers/01-asw.css";
+@import "./layers/01-tokens.css";
 @import "./layers/02-semantic.css";
 @import "./layers/03-components.css";
 @import "./layers/04-data-attrs.css";