feat(api): add dedicated /health endpoint with timestamp

Separate root route from health check endpoint. The /health endpoint
now returns timestamp for monitoring integration.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/app.controller.ts

@@ -3,7 +3,12 @@ import { Controller, Get } from '@nestjs/common';
 @Controller()
 export class AppController {
   @Get()
-  healthCheck() {
+  root() {
     return { status: 'ok', service: 'goodgo-api' };
   }
+
+  @Get('health')
+  healthCheck() {
+    return { status: 'ok', service: 'goodgo-api', timestamp: new Date().toISOString() };
+  }
 }