feat(delivery): add supplier article lookup, article creation, and unified parsing

- Unified PDF/TXT parsing to single POST /api/delivery/parse endpoint
- Added supplier article lookup with SKU/EAN matching in delivery lines
- Added "Artikel anlegen" button to create articles from missing SKUs
- Fixed delivery line taxrate field (was sending 'tax', now 'taxrate')
- Extended TXT file support for rescan functionality
- Updated ApiClient with getArticles method for supplier article lookup
- Added supplier article state management to deliveryEditorAutomat

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

src/api/index.js

@@ -611,6 +611,22 @@ export const supplier = {
   delete(id) {
     return http(`/api/supplier/${id}`, { method: 'DELETE' });
   },
+
+  /**
+   * GET /api/supplier/:id/articles?skus=...
+   * → 200 { articles: SupplierArticle[] }
+   */
+  getArticles(id, skus) {
+    let query = '';
+    if (skus != null) {
+      const list = Array.isArray(skus) ? skus : [skus];
+      const filtered = list.map((s) => String(s).trim()).filter(Boolean);
+      if (filtered.length > 0) {
+        query = `?skus=${encodeURIComponent(filtered.join(','))}`;
+      }
+    }
+    return http(`/api/supplier/${encodeURIComponent(id)}/articles${query}`);
+  },
 };
 
 /**
@@ -662,18 +678,6 @@ export const delivery = {
     return http(`/api/delivery/${id}`, { method: 'DELETE' });
   },
 
-  /**
-   * POST /api/delivery/parse-pdf
-   * Body: raw PDF bytes (Content-Type: application/pdf)
-   */
-  parsePdf(file) {
-    return httpBinary('/api/delivery/parse-pdf', {
-      method: 'POST',
-      contentType: 'application/pdf',
-      body: file,
-      headers: file?.name ? { 'X-Filename': encodeURIComponent(file.name) } : undefined,
-    });
-  },
 };
 
 /**