feat: add Code OS project-info prompt template to scaffold

Adds .prompts/project-info.prompttemplate to the Turborepo scaffold so
every new user project gets a customized context file loaded by the Code
OS agent — including build commands, workspace structure, and shared
package import paths with the project's actual slug injected.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/scaffold/turborepo/.prompts/project-info.prompttemplate

@@ -0,0 +1,67 @@
+## Project: {{project-name}}
+
+This is a **Turborepo monorepo** project named `{{project-slug}}`, built with Next.js and pnpm workspaces.
+
+### Workspace Structure
+
+```
+apps/
+  product/     ← main user-facing Next.js application
+  website/     ← marketing / landing site (Next.js)
+  admin/       ← internal admin panel (Next.js)
+  storybook/   ← component browser for packages/ui
+
+packages/
+  ui/          ← shared React components (@{{project-slug}}/ui)
+  tokens/      ← design tokens — CSS variables + TypeScript (@{{project-slug}}/tokens)
+  types/       ← shared TypeScript interfaces and types (@{{project-slug}}/types)
+  config/      ← shared tsconfig and eslint config (@{{project-slug}}/config)
+```
+
+### Build Commands (always run from repo root)
+
+| Task | Command |
+|------|---------|
+| Install dependencies | `pnpm install` |
+| Build one app | `pnpm turbo run build --filter=product` |
+| Build all apps | `pnpm turbo run build` |
+| Dev one app | `pnpm turbo run dev --filter=product` |
+| Dev all | `pnpm turbo run dev` |
+| Lint | `pnpm turbo run lint` |
+| Type-check | `pnpm turbo run type-check` |
+| Add dep to app | `pnpm add <pkg> --filter=product` |
+| Add dep to package | `pnpm add <pkg> --filter=@{{project-slug}}/ui` |
+
+### Shared Package Imports
+
+Always import workspace packages by their scoped name:
+
+```typescript
+import { Button } from '@{{project-slug}}/ui';
+import type { User } from '@{{project-slug}}/types';
+import '@{{project-slug}}/tokens/css'; // CSS variables
+```
+
+Reference in `package.json` dependencies:
+```json
+{ "@{{project-slug}}/ui": "workspace:*" }
+```
+
+### Key Rules
+
+- **Never** use `npm install` — always `pnpm install` from the repo root
+- **Never** run `next build` or `next dev` directly inside an app directory — use `turbo run` from root
+- **Always** add dependencies with `--filter` to target the correct workspace
+- Turbo caches build outputs in `.turbo/` — run `pnpm turbo run clean` to clear cache
+- The `packages/config` package exports shared `tsconfig.base.json` and eslint config
+
+### Apps Overview
+
+- **product**: The primary user-facing Next.js app. Port `3000` in dev.
+- **website**: Marketing site. Port `3001` in dev.
+- **admin**: Admin panel. Port `3002` in dev.
+- **storybook**: Visual component browser for `packages/ui`. Port `6006` in dev.
+
+### Next.js App Router
+
+All apps use the Next.js App Router (`app/` directory). Page files are `page.tsx`, layouts are `layout.tsx`.