fix: add /health proxy rule to Vite config

- Vite now forwards /health to Rust proxy (port 8888)
- Required for Admin Panel proxy health check to work in dev mode
- External Caddy reverse proxy may also need /health forwarding rule

vite.config.ts

@@ -35,6 +35,10 @@ export default defineConfig({
       '/api/v2': {
         target: 'http://localhost:11438',
         changeOrigin: true
+      },
+      '/health': {
+        target: 'http://localhost:8888',
+        changeOrigin: true
       }
     }
   }