Backend frontend sync

Synchronized frontend and backend with login and register endpoint working

FullstackProsjekt/src/backend/main/java/edu/ntnu/idatt2105/configuration/CorsConfig.java

+package edu.ntnu.idatt2105.configuration;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class CorsConfig implements WebMvcConfigurer {
+  @Override
+  public void addCorsMappings(CorsRegistry registry) {
+    registry.addMapping("/**")
+        .allowedOrigins("http://localhost:4173")
+        .allowedMethods("GET", "POST", "PUT", "DELETE")
+        .allowedHeaders("*");
+  }
+}