feat: add 33 skills from vudovn/antigravity-kit

- Added: api-patterns, app-builder, architecture, bash-linux, behavioral-modes,
  clean-code, code-review-checklist, database-design, deployment-procedures,
  docker-expert, documentation-templates, game-development, geo-fundamentals,
  i18n-localization, lint-and-validate, mobile-design, nestjs-expert,
  nextjs-best-practices, nodejs-best-practices, parallel-agents,
  performance-profiling, plan-writing, powershell-windows, prisma-expert,
  python-patterns, react-patterns, red-team-tactics, seo-fundamentals,
  server-management, tailwind-patterns, tdd-workflow, typescript-expert,
  vulnerability-scanner
- Updated README: skill count 179 → 223
- Added credit for vudovn/antigravity-kit (MIT License)

Source: https://github.com/vudovn/antigravity-kit

skills/app-builder/scaffolding.md

@@ -0,0 +1,118 @@
+# Project Scaffolding
+
+> Directory structure and core files for new projects.
+
+---
+
+## Next.js Full-Stack Structure (2025 Optimized)
+
+```
+project-name/
+├── src/
+│   ├── app/                        # Routes only (thin layer)
+│   │   ├── layout.tsx
+│   │   ├── page.tsx
+│   │   ├── globals.css
+│   │   ├── (auth)/                 # Route group - auth pages
+│   │   │   ├── login/page.tsx
+│   │   │   └── register/page.tsx
+│   │   ├── (dashboard)/            # Route group - dashboard layout
+│   │   │   ├── layout.tsx
+│   │   │   └── page.tsx
+│   │   └── api/
+│   │       └── [resource]/route.ts
+│   │
+│   ├── features/                   # Feature-based modules
+│   │   ├── auth/
+│   │   │   ├── components/
+│   │   │   ├── hooks/
+│   │   │   ├── actions.ts          # Server Actions
+│   │   │   ├── queries.ts          # Data fetching
+│   │   │   └── types.ts
+│   │   ├── products/
+│   │   │   ├── components/
+│   │   │   ├── actions.ts
+│   │   │   └── queries.ts
+│   │   └── cart/
+│   │       └── ...
+│   │
+│   ├── shared/                     # Shared utilities
+│   │   ├── components/ui/          # Reusable UI components
+│   │   ├── lib/                    # Utils, helpers
+│   │   └── hooks/                  # Global hooks
+│   │
+│   └── server/                     # Server-only code
+│       ├── db/                     # Database client (Prisma)
+│       ├── auth/                   # Auth config
+│       └── services/               # External API integrations
+│
+├── prisma/
+│   ├── schema.prisma
+│   ├── migrations/
+│   └── seed.ts
+│
+├── public/
+├── .env.example
+├── .env.local
+├── package.json
+├── tailwind.config.ts
+├── tsconfig.json
+└── README.md
+```
+
+---
+
+## Structure Principles
+
+| Principle | Implementation |
+|-----------|----------------|
+| **Feature isolation** | Each feature in `features/` with its own components, hooks, actions |
+| **Server/Client separation** | Server-only code in `server/`, prevents accidental client imports |
+| **Thin routes** | `app/` only for routing, logic lives in `features/` |
+| **Route groups** | `(groupName)/` for layout sharing without URL impact |
+| **Shared code** | `shared/` for truly reusable UI and utilities |
+
+---
+
+## Core Files
+
+| File | Purpose |
+|------|---------|
+| `package.json` | Dependencies |
+| `tsconfig.json` | TypeScript + path aliases (`@/features/*`) |
+| `tailwind.config.ts` | Tailwind config |
+| `.env.example` | Environment template |
+| `README.md` | Project documentation |
+| `.gitignore` | Git ignore rules |
+| `prisma/schema.prisma` | Database schema |
+
+---
+
+## Path Aliases (tsconfig.json)
+
+```json
+{
+  "compilerOptions": {
+    "paths": {
+      "@/*": ["./src/*"],
+      "@/features/*": ["./src/features/*"],
+      "@/shared/*": ["./src/shared/*"],
+      "@/server/*": ["./src/server/*"]
+    }
+  }
+}
+```
+
+---
+
+## When to Use What
+
+| Need | Location |
+|------|----------|
+| New page/route | `app/(group)/page.tsx` |
+| Feature component | `features/[name]/components/` |
+| Server action | `features/[name]/actions.ts` |
+| Data fetching | `features/[name]/queries.ts` |
+| Reusable button/input | `shared/components/ui/` |
+| Database query | `server/db/` |
+| External API call | `server/services/` |