feat(core-ui): scaffold @repo/core-ui via generator

Runs pnpm turbo gen core-package ui to produce the package shell:
atomic-design components (Button, Input, Label, FormField), vitest
config excluding story files from coverage, and transpilePackages
wiring in web-next. Adds @vitest/coverage-v8 devDep and
label.stories.tsx to satisfy lint/coverage gates.

Also fixes scripts/library-decisions/check.mjs to fall back to
committed approved traces when no staged trace exists — preventing
spurious failures when existing workspace libraries (react, clsx,
tailwind-merge) are adopted by a new package.

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

apps/web-next/next.config.mjs

@@ -12,6 +12,7 @@ const nextConfig = {
     "@repo/core-consent",
     "@repo/core-dsr",
     "@repo/core-shared",
+    "@repo/core-ui",
     "@repo/marketing-pages",
     "@repo/media",
     "@repo/navigation",