Add FlatPaymentController with RESTful payment endpoints

Introduced FlatPaymentController under Distribution.Features.Payment, providing GET and POST endpoints at /api/payments. Supports listing, retrieving, and creating payments with filtering and error handling. Business logic is delegated to PaymentService.

distribution_fe/lib/api/catalogue.ts

@@ -75,10 +75,13 @@ export const categories = {
     api.put<CategoryResponse>(`/categories/${id}`, body).then(r => r.data),
 
   createSubCategory: (categoryId: string, body: SubCategoryBody) =>
-    api.post(`/categories/${categoryId}/sub-categories`, body).then(r => r.data),
+    api.post(`/categories/${categoryId}/subcategories`, body).then(r => r.data),
 
-  updateSubCategory: (categoryId: string, subId: string, body: Partial<SubCategoryBody>) =>
-    api.put(`/categories/${categoryId}/sub-categories/${subId}`, body).then(r => r.data),
+  updateSubCategory: (_categoryId: string, subId: string, body: Partial<SubCategoryBody>) =>
+    api.put(`/subcategories/${subId}`, body).then(r => r.data),
+
+  deleteSubCategory: (subId: string) =>
+    api.delete(`/subcategories/${subId}`),
 }
 
 // ─── Brands ───────────────────────────────────────────────────────────────────