feat: initial website commit + installation guide page

- Full nixpanel-website monorepo: web (React/Vite) + api (Fastify)
- Add /install page with one-liner, manual steps, requirements,
  software table, firewall ports, service management, and update/uninstall
- Add Install link to header nav and footer
- Add 'Install guide' CTA button to home page hero
- Add 'outline' variant to Button component
- Add .gitignore and .gitattributes

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

web/vite.config.ts

@@ -0,0 +1,19 @@
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+import path from 'path';
+
+export default defineConfig({
+  plugins: [react()],
+  resolve: {
+    alias: { '@': path.resolve(__dirname, './src') },
+  },
+  server: {
+    port: 5173,
+    proxy: {
+      '/api': {
+        target: 'http://localhost:4000',
+        changeOrigin: true,
+      },
+    },
+  },
+});