Add collections for photography portfolio website:
- PortfolioCategories: categories with name, slug, cover image, order
- Portfolios: galleries with images, project details, SEO fields
- Both collections are tenant-scoped and localized (DE/EN)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
