feat(webui): add Tailwind build system and refactor frontend architecture

- Replace Tailwind CDN with local build (PostCSS + autoprefixer + daisyui)

- Add CSS build scripts with automatic prepare hook on npm install

- Create account-actions.js service layer with unified response format

- Extend ErrorHandler.withLoading() for automatic loading state management

- Add skeleton screens for initial load, silent refresh for subsequent updates

- Implement loading animations for async operations (buttons, modals)

- Improve empty states and add ARIA labels for accessibility

- Abstract component styles using @apply (buttons, badges, inputs)

- Add JSDoc documentation for Dashboard modules

- Update README and CLAUDE.md with development guidelines

README.md

@@ -458,6 +458,63 @@ By using this software, you acknowledge and accept the following:
 
 ---
 
+## Development
+
+### For Developers & Contributors
+
+This project uses a local Tailwind CSS build system. CSS is pre-compiled and included in the repository, so you can run the project immediately after cloning.
+
+#### Quick Start
+
+```bash
+git clone https://github.com/badri-s2001/antigravity-claude-proxy.git
+cd antigravity-claude-proxy
+npm install  # Automatically builds CSS via prepare hook
+npm start    # Start server (no rebuild needed)
+```
+
+#### Frontend Development
+
+If you need to modify styles in `public/css/src/input.css`:
+
+```bash
+# Option 1: Build once
+npm run build:css
+
+# Option 2: Watch for changes (auto-rebuild)
+npm run watch:css
+
+# Option 3: Watch both CSS and server (recommended)
+npm run dev:full
+```
+
+**File Structure:**
+- `public/css/src/input.css` - Source CSS with Tailwind `@apply` directives (edit this)
+- `public/css/style.css` - Compiled & minified CSS (auto-generated, don't edit)
+- `tailwind.config.js` - Tailwind configuration
+- `postcss.config.js` - PostCSS configuration
+
+#### Backend-Only Development
+
+If you're only working on backend code and don't need frontend dev tools:
+
+```bash
+npm install --production  # Skip devDependencies (saves ~20MB)
+npm start
+```
+
+**Note:** Pre-compiled CSS is committed to the repository, so you don't need to rebuild unless modifying styles.
+
+#### Project Structure
+
+See [CLAUDE.md](./CLAUDE.md) for detailed architecture documentation, including:
+- Request flow and module organization
+- Frontend architecture (Alpine.js + Tailwind)
+- Service layer patterns (`ErrorHandler.withLoading`, `AccountActions`)
+- Dashboard module documentation
+
+---
+
 ## Credits
 
 This project is based on insights and code from: