feat: add starter templates gallery

[bntvllnt]

Summary

• Add /templates and /templates/[slug] routes for five starter kits: next-starter, dashboard, saas, ai-chat, and docs-site.
• Add shared template metadata, screenshots, README/template manifests under templates/<slug>/, SoftwareApplication JSON-LD, sitemap entries, and llms.txt/llms-full.txt template sections.
• Link templates from the home hero, header/sidebar navigation, and the shadcn comparison page.

Validation

• pnpm -F @vllnt/ui-registry exec tsc --noEmit --project tsconfig.json
• npx --yes react-doctor . --diff origin/main --annotations --fail-on error --offline
• pnpm -F @vllnt/ui lint
• pnpm -F @vllnt/ui exec tsc --noEmit --project tsconfig.build.json
• pnpm build
• pnpm test:once
• git diff --check

Notes: install snippets use pnpm dlx create-vllnt-app@latest --template <slug> to honor the repo pnpm-only rule. pnpm build still emits the known Next.js multiple-lockfile worktree warning. pnpm test:once still emits existing jsdom navigation, ShareDialog description, and InteractiveTimeline duplicate-key warnings while passing all tests.

Closes #259

[vercel]

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Project	Deployment	Actions	Updated (UTC)
storybook	Ready	Preview, Comment	May 12, 2026 10:18pm
ui.vllnt.ai	Ready	Preview, Comment	May 12, 2026 10:18pm