feat(storybook): wire @storybook/test-runner for story smoke tests

Every story is now executed as a smoke test (mount + no console errors)
via @storybook/test-runner. New script: pnpm test:stories runs
build-storybook then test-storybook against the static build.

Spec: §6.8

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/storybook/package.json

@@ -6,8 +6,11 @@
   "scripts": {
     "build": "echo 'Storybook build — use pnpm dev for development'",
     "build:storybook": "storybook build",
+    "build-storybook": "storybook build",
     "dev": "storybook dev -p 6006",
-    "lint": "eslint ."
+    "lint": "eslint .",
+    "test-storybook": "test-storybook --url http://localhost:6006",
+    "test:stories": "concurrently -k -s first -n 'SB,TEST' -c 'magenta,blue' 'pnpm exec http-server storybook-static --port 6006 --silent' 'pnpm exec wait-on tcp:6006 && pnpm test-storybook'"
   },
   "dependencies": {
     "@repo/core-ui": "workspace:*"
@@ -18,11 +21,16 @@
     "@storybook/addon-essentials": "^8.6.0",
     "@storybook/react": "^8.6.0",
     "@storybook/react-vite": "^8.6.0",
+    "@storybook/test-runner": "^0.19.1",
     "@tailwindcss/vite": "^4.1.0",
+    "concurrently": "^9.0.0",
+    "http-server": "^14.1.0",
+    "playwright": "^1.52.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "storybook": "^8.6.0",
     "tailwindcss": "^4.1.0",
-    "vite": "^6.3.0"
+    "vite": "^6.3.0",
+    "wait-on": "^8.0.0"
   }
 }