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)

AGENTS.md

@@ -0,0 +1,19 @@
+# Web3 Style Guide — Engineering Standards
+
+- **Minimal-Change Fixes:** Verify flaws before patching; touch only what the task requires.
+- **Token-First:** Always reference CSS custom properties instead of raw hex/rgb values.
+- **Verification:** Run `npm run build` before declaring work finished.
+- **Atomic Commits:** Small, clear, descriptive commits (`feat:`, `fix:`, `chore:`, `tokens:`).
+
+## Current Status
+- Tokens: colors, typography, spacing — extracted from dao-marketplace
+- Components: base, card, button, forms — extracted and generalized
+- Showcase: interactive Vite app with tabbed navigation
+- Build: passes (vite v8.2.2)
+
+## Roadmap
+- [ ] Add React component library (pixel-card, pixel-btn, etc.)
+- [ ] Add dark/light theme toggle
+- [ ] Add Figma token export
+- [ ] Add Storybook for component documentation
+- [ ] Publish as npm package `@web3/style-guide`