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/templates/electron-desktop/TEMPLATE.md

@@ -0,0 +1,88 @@
+---
+name: electron-desktop
+description: Electron desktop app template principles. Cross-platform, React, TypeScript.
+---
+
+# Electron Desktop App Template
+
+## Tech Stack
+
+| Component | Technology |
+|-----------|------------|
+| Framework | Electron 28+ |
+| UI | React 18 |
+| Language | TypeScript |
+| Styling | Tailwind CSS |
+| Bundler | Vite + electron-builder |
+| IPC | Type-safe communication |
+
+---
+
+## Directory Structure
+
+```
+project-name/
+├── electron/
+│   ├── main.ts          # Main process
+│   ├── preload.ts       # Preload script
+│   └── ipc/             # IPC handlers
+├── src/
+│   ├── App.tsx
+│   ├── components/
+│   │   ├── TitleBar.tsx # Custom title bar
+│   │   └── ...
+│   └── hooks/
+├── public/
+└── package.json
+```
+
+---
+
+## Process Model
+
+| Process | Role |
+|---------|------|
+| Main | Node.js, system access |
+| Renderer | Chromium, React UI |
+| Preload | Bridge, context isolation |
+
+---
+
+## Key Concepts
+
+| Concept | Purpose |
+|---------|---------|
+| contextBridge | Safe API exposure |
+| ipcMain/ipcRenderer | Process communication |
+| nodeIntegration: false | Security |
+| contextIsolation: true | Security |
+
+---
+
+## Setup Steps
+
+1. `npm create vite {{name}} -- --template react-ts`
+2. Install: `npm install -D electron electron-builder vite-plugin-electron`
+3. Create electron/ directory
+4. Configure main process
+5. `npm run electron:dev`
+
+---
+
+## Build Targets
+
+| Platform | Output |
+|----------|--------|
+| Windows | NSIS, Portable |
+| macOS | DMG, ZIP |
+| Linux | AppImage, DEB |
+
+---
+
+## Best Practices
+
+- Use preload script for main/renderer bridge
+- Type-safe IPC with typed handlers
+- Custom title bar for native feel
+- Handle window state (maximize, minimize)
+- Auto-updates with electron-updater