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)

README.md

@@ -0,0 +1,72 @@
+# Web3 Corporate Style Guide
+
+A shared design system for products across the Web3 ecosystem. Derived from the visual language of the DAO Marketplace project.
+
+## Quick Start
+
+```bash
+npm install
+npm run dev     # Vite dev server with live component showcase
+npm run build   # Production build
+```
+
+## Repository Structure
+
+```
+src/
+├── tokens/              # Design tokens (CSS custom properties)
+│   ├── index.css        # Master token import
+│   ├── colors.css       # Color palette
+│   ├── typography.css   # Font families, sizes, weights
+│   └── spacing.css      # Layout dimensions, radii, gaps
+├── css/                 # Component stylesheets
+│   ├── web3-style.css   # Master stylesheet (imports all below)
+│   ├── base.css         # Reset, header, nav, main, responsive
+│   ├── card.css         # .pixel-card component
+│   ├── button.css       # .pixel-btn component
+│   └── forms.css        # Form controls, footer, grids
+├── components/          # (reserved for future React/Vue components)
+├── App.tsx              # Interactive showcase app
+├── main.tsx             # Entry point
+└── demo.css             # Showcase-specific styles
+```
+
+## Integration
+
+### Option A: Full CSS Import
+```css
+@import "@web3/style-guide/css/web3-style.css";
+```
+
+### Option B: Tokens Only
+```css
+@import "@web3/style-guide/tokens/index.css";
+```
+
+### Option C: Individual Components
+```css
+@import "@web3/style-guide/css/card.css";
+@import "@web3/style-guide/css/button.css";
+```
+
+## Design Language
+
+| Token | Value | Usage |
+|-------|-------|-------|
+| `--color-bg-primary` | `#0c1020` | Page background |
+| `--color-accent-green` | `#59d8ae` | Brand indicator, success |
+| `--color-accent-blue` | `#6f8bff` | Buttons, focus rings |
+| `--color-text-primary` | `#e7eaf1` | Body text |
+| `--font-family-base` | `Inter, system-ui, ...` | All UI text |
+
+## Brand Conventions
+
+- **Dark-first**: All views use `#0c1020` with radial mesh gradients
+- **Green status dot**: 10px glowing indicator in product headers
+- **Blue interactive**: Buttons and focus rings use `#6f8bff`
+- **Floating footer**: Fixed bottom bar with backdrop blur
+- **Glassmorphism**: Cards use `rgba(21,27,48,.82)` with `backdrop-filter`
+
+## License
+
+Internal use across Web3 ecosystem products.