feat: health check for backend in docker-compose;

feat: go dockerfile preinstalls curl;
refactor: reduced go image size by using a 2 stage dockerfile;
refactor: switch frontend dockerfile

docker-compose.yml

@@ -3,6 +3,13 @@ services:
   backend:
     build: ./backend
     restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "/usr/bin/curl", "-f", "http://localhost:8080/service/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3 
+    ports:
+      - "8080:8080"
     networks:
       - easywish-network