fix: Update nginx config to use dynamic DNS resolution

- Replace upstream blocks with resolver directive
- Use variables for backend addresses to avoid startup errors
- Simplify configuration with single server block
- Add health check endpoint

server/api/node_modules/resolve/test/node_path/y/bbb/index.js

@@ -0,0 +1 @@
+module.exports = 'B';

server/api/node_modules/resolve/test/node_path/y/ccc/index.js

@@ -0,0 +1 @@
+module.exports = 'CY';