feat(cors): implement cors

ilp-rest-service/src/main/java/io/github/js0ny/ilp_coursework/config/CorsConfig.java

@@ -0,0 +1,27 @@
+package io.github.js0ny.ilp_coursework.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+/**
+ * Global CORS configuration so the frontend running on a different port can call the REST API.
+ */
+@Configuration
+public class CorsConfig implements WebMvcConfigurer {
+
+    private static final String[] ALLOWED_ORIGINS = new String[] {
+            "http://localhost:4173",
+            "http://127.0.0.1:4173",
+            "http://localhost:5173",
+            "http://127.0.0.1:5173"
+    };
+
+    @Override
+    public void addCorsMappings(CorsRegistry registry) {
+        registry.addMapping("/**")
+                .allowedOrigins(ALLOWED_ORIGINS)
+                .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS", "HEAD", "PATCH")
+                .allowedHeaders("*");
+    }
+}