feat(ap1): add vanilla SPA PKCE login

backend/src/main/java/com/example/keycloakpattern/SecurityConfig.java

@@ -1,11 +1,16 @@
 package com.example.keycloakpattern;
 
+import java.util.List;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.security.config.Customizer;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
 import org.springframework.security.config.http.SessionCreationPolicy;
 import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.web.cors.CorsConfiguration;
+import org.springframework.web.cors.CorsConfigurationSource;
+import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
 
 @Configuration
 public class SecurityConfig {
@@ -13,6 +18,7 @@ public class SecurityConfig {
     @Bean
     SecurityFilterChain apiSecurity(HttpSecurity http) throws Exception {
         return http
+            .cors(Customizer.withDefaults())
             .csrf(csrf -> csrf.disable())
             .sessionManagement(session ->
                 session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
@@ -24,4 +30,19 @@ public class SecurityConfig {
             .oauth2ResourceServer(oauth2 -> oauth2.jwt(Customizer.withDefaults()))
             .build();
     }
+
+    @Bean
+    CorsConfigurationSource corsConfigurationSource() {
+        CorsConfiguration configuration = new CorsConfiguration();
+        configuration.setAllowedOrigins(List.of(
+            "http://localhost:8088",
+            "http://127.0.0.1:8088"
+        ));
+        configuration.setAllowedMethods(List.of("GET", "OPTIONS"));
+        configuration.setAllowedHeaders(List.of("Authorization", "Content-Type"));
+
+        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
+        source.registerCorsConfiguration("/api/**", configuration);
+        return source;
+    }
 }