feat(article): add article import with V/K compound linking

Add article.importRows to create articles by SKU from CSV-style rows,
running in two passes so fatherSku links to rows later in the file still
resolve. Existing SKUs are skipped, duplicate EANs are dropped, prices and
taxes are ensured, brands are upserted by name, and parent categories are
resolved/created via breadcrumb path.

Also add:
- article.setFatherBySku to link/unlink a child to its father article
- category.ensureByPath to resolve or create categories by path (tx-aware)
- supporting SQL constants (GET_ID_BY_SKU, EAN_EXISTS, father-link helpers,
  GET_BY_PARENT_AND_NAME)
- regenerated API docs

src/sql/article.js

@@ -59,6 +59,39 @@ INNER JOIN categoryarticle ca ON ca.article_id = a.id
 WHERE a.sku = @sku
 `;
 
+/** Resolve an article id by sku (used to wire father/child compound links). */
+export const GET_ID_BY_SKU = `
+SELECT TOP 1 id AS articleId
+FROM article
+WHERE sku = @sku
+`;
+
+/** True if an EAN is already assigned to any article (duplicate guard). */
+export const EAN_EXISTS = `
+SELECT TOP 1 1 AS used
+FROM articleean
+WHERE ean = @ean
+`;
+
+/** Link an article to its father article and mark the father. */
+export const UPDATE_FATHER_BY_SKU = `
+UPDATE article
+SET fatherarticle_id = @fatherArticleId
+WHERE sku = @sku
+`;
+
+export const SET_IS_FATHER = `
+UPDATE article
+SET is_father = 1
+WHERE id = @articleId
+`;
+
+export const SET_FATHER_SORT = `
+UPDATE article
+SET fathersort = @fathersort
+WHERE id = @articleId AND fatherarticle_id = @fatherArticleId
+`;
+
 /** SKU → article/category + company auth in one round-trip. */
 export const RESOLVE_ARTICLE_ACCESS_BY_SKU = `
 WITH article_cat AS (

src/sql/category.js

@@ -92,6 +92,16 @@ FROM category
 WHERE parent_id = @parentId
 `;
 
+/** Resolve a child category by its parent id and name (language-sensitive). */
+export const GET_BY_PARENT_AND_NAME = `
+SELECT c.id
+FROM category c
+INNER JOIN categorytext ct
+    ON ct.category_id = c.id AND ct.language_id = @languageId
+WHERE c.parent_id = @parentId
+  AND ct.name = @name
+`;
+
 export const LIST_CHILD_IDS = `
 SELECT id
 FROM category