docs: refactor README by moving sections to docs/ folder

Move 11 documentation sections to separate markdown files in docs/:
- models.md, load-balancing.md, web-console.md, configuration.md
- menubar-app.md, api-endpoints.md, testing.md, troubleshooting.md
- safety-notices.md, legal.md, development.md

README now contains a Documentation section with links to each doc.
Also moved donation link to above Star History section.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/development.md

@@ -0,0 +1,54 @@
+# 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