feat(dashboard): React frontend scaffold with overview page

- Vite + React 18 + TypeScript + Tailwind CSS
- Dashboard overview with health gauge, pillar bars, alerts
- WebSocket hook for real-time updates
- Layout with sidebar navigation and live indicator
- Placeholder pages for Mesh, Environment, Config, Alerts
- Dark theme ops center aesthetic with JetBrains Mono

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

dashboard-frontend/tailwind.config.ts

@@ -0,0 +1,26 @@
+import type { Config } from 'tailwindcss'
+
+export default {
+  content: ['./index.html', './src/**/*.{ts,tsx}'],
+  darkMode: 'class',
+  theme: {
+    extend: {
+      colors: {
+        bg: {
+          DEFAULT: '#0a0e17',
+          card: '#111827',
+          hover: '#1a2332',
+        },
+        border: {
+          DEFAULT: '#1e2a3a',
+          light: '#2d3a4d',
+        },
+        accent: '#3b82f6',
+      },
+      fontFamily: {
+        mono: ['JetBrains Mono', 'monospace'],
+      },
+    },
+  },
+  plugins: [],
+} satisfies Config