feat: initial web3 corporate style guide

- Extract design tokens (colors, typography, spacing) from dao-marketplace
- Build component CSS: base, card, button, forms
- Create interactive Vite showcase app with tabbed navigation
- Add README, .gitignore, AGENTS.md
- Build passes (vite v8.2.2)

package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@web3/style-guide",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "lint": "eslint src --ext ts,tsx,css"
+  },
+  "dependencies": {
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1"
+  },
+  "devDependencies": {
+    "@types/react": "^18.3.0",
+    "@types/react-dom": "^18.3.0",
+    "@vitejs/plugin-react": "^4.3.0",
+    "typescript": "^5.6.0",
+    "vite": "^8.2.2"
+  }
+}