feat: rename WHM→NixServer, cPanel→NixClient, bump v0.2.0

- Rename frontend workspaces: whm/ → nixserver/, cpanel/ → nixclient/
- Rename server route dirs: routes/whm/ → routes/nixserver/, routes/cpanel/ → routes/nixclient/
- Update all API prefixes: /api/whm → /api/nixserver, /api/cpanel → /api/nixclient
- Rename env vars: WHM_PORT → NIXSERVER_PORT, CPANEL_PORT → NIXCLIENT_PORT
- Update config properties: whmPort → nixserverPort, cpanelPort → nixclientPort
- Update all UI labels, login pages, sidebar branding, and error messages
- Update installer and update scripts to match new names
- Add cpanel email route (missing from initial scaffold)
- Add .gitattributes to enforce LF line endings
- Bump version to 0.2.0 across all package.json files

nixclient/tailwind.config.js

@@ -0,0 +1,16 @@
+/** @type {import('tailwindcss').Config} */
+export default {
+  content: ['./index.html', './src/**/*.{js,ts,jsx,tsx}'],
+  theme: {
+    extend: {
+      colors: {
+        primary: '#0a0f1a',
+        secondary: '#111827',
+        card: '#1a2235',
+        border: '#1e2d45',
+        accent: '#0ea5e9',
+      },
+    },
+  },
+  plugins: [],
+}