feat: Implement reference data management for states, transport modes, transport types, and valuation methods

- Added server-side loading logic for states, transport modes, transport types, and valuation methods with pagination support.
- Created Svelte components for displaying and managing states, transport modes, transport types, and valuation methods.
- Implemented infinite scroll functionality for loading more data as the user scrolls.
- Added error handling and user feedback for API interactions.
- Included dialogs for creating and editing entries in each reference data category.

frontend/src/lib/api/dashboard/refrence_data/customs_sections.ts

@@ -0,0 +1,69 @@
+/**
+ * API Client para Customs Sections
+ * Gestiona las operaciones CRUD para las secciones aduaneras
+ */
+import { api } from '$lib/api';
+
+export interface CustomsSection {
+	customs_code: string;
+	section_name: string;
+}
+
+export interface CustomsSectionListResponse {
+	items: CustomsSection[];
+	total: number;
+	page: number;
+	page_size: number;
+}
+
+export interface CreateCustomsSectionData {
+	customs_code: string;
+	section_name: string;
+}
+
+export interface UpdateCustomsSectionData {
+	customs_code?: string;
+	section_name?: string;
+}
+
+/**
+ * API para Customs Sections
+ */
+export const customsSectionsApi = {
+	/**
+	 * Lista todas las secciones aduaneras con paginación
+	 * @param page - Número de página (por defecto 1)
+	 * @param pageSize - Tamaño de página (por defecto 50)
+	 */
+	list: (page = 1, pageSize = 50) =>
+		api.get<CustomsSectionListResponse>(
+			`/v1/customs-sections?page=${page}&page_size=${pageSize}`
+		),
+
+	/**
+	 * Obtiene una sección aduanera por código
+	 * @param customs_code - Código de la sección aduanera
+	 */
+	get: (customs_code: string) => api.get<CustomsSection>(`/v1/customs-sections/${customs_code}`),
+
+	/**
+	 * Crea una nueva sección aduanera
+	 * @param data - Datos de la sección aduanera a crear
+	 */
+	create: (data: CreateCustomsSectionData) =>
+		api.post<CustomsSection>('/v1/customs-sections', data),
+
+	/**
+	 * Actualiza una sección aduanera existente
+	 * @param customs_code - Código de la sección aduanera a actualizar
+	 * @param data - Datos a actualizar
+	 */
+	update: (customs_code: string, data: UpdateCustomsSectionData) =>
+		api.put<CustomsSection>(`/v1/customs-sections/${customs_code}`, data),
+
+	/**
+	 * Elimina una sección aduanera
+	 * @param customs_code - Código de la sección aduanera a eliminar
+	 */
+	delete: (customs_code: string) => api.delete(`/v1/customs-sections/${customs_code}`)
+};