feat(sw): prepare reusable AI-friendly component package

- Ship an AI guide in the package (ai/: usage rules, component catalog,
  design rules, composition patterns) via package.json files.
- Add examples A-D that import only public exports: default header,
  viewer header, feature header, and a consumer-side search extension
  that reuses SWHeaderInput and the public SW tokens.
- Add SW-only checks: docs/API consistency, tarball consumer project
  (React 19 + TS + Vite typecheck/build) and a browser check (27/27).
- No runtime source or public API change; README gains a pointer section.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/sw/package.json

@@ -15,7 +15,8 @@
     "./styles.css": "./dist/styles.css"
   },
   "files": [
-    "dist"
+    "dist",
+    "ai"
   ],
   "scripts": {
     "typecheck": "tsc -p tsconfig.json",