Set up parent category mechanism.

codiki-exposition/src/main/java/org/codiki/exposition/category/CategoryController.java

@@ -1,5 +1,6 @@
 package org.codiki.exposition.category;
 
+import java.util.List;
 import java.util.UUID;
 
 import static org.springframework.http.HttpStatus.CREATED;
@@ -9,6 +10,7 @@ import org.codiki.domain.category.model.Category;
 import org.codiki.exposition.category.model.CategoryDto;
 import org.codiki.exposition.category.model.CategoryEditionRequest;
 import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.PutMapping;
@@ -51,4 +53,12 @@ public class CategoryController {
     public void deleteCategory(@PathVariable("categoryId") UUID categoryId) {
         categoryUseCases.deleteCategory(categoryId);
     }
+
+    @GetMapping
+    public List<CategoryDto> getAllCategories() {
+        return categoryUseCases.getAll()
+            .stream()
+            .map(CategoryDto::new)
+            .toList();
+    }
 }

codiki-exposition/src/main/java/org/codiki/exposition/configuration/security/SecurityConfiguration.java

@@ -43,6 +43,7 @@ public class SecurityConfiguration {
                 .requestMatchers(
                     GET,
                     "/api/health/check",
+                    "/api/categories",
                     "/error"
                 ).permitAll()
                 .requestMatchers(