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/ApiClient.js

@@ -80,6 +80,18 @@ export class ApiClient {
       update: (id, body) => this.#json('PATCH', `/api/supplier/${enc(id)}`, { body }),
       /** DELETE /api/supplier/{id} → 204 */
       delete: (id) => this.#empty('DELETE', `/api/supplier/${enc(id)}`),
+      /** GET /api/supplier/{id}/articles?skus=... → { 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=${encodeURIComponent(filtered.join(','))}`;
+          }
+        }
+        return this.#json('GET', `/api/supplier/${enc(id)}/articles${query}`);
+      },
     };
 
     this.delivery = {
@@ -94,14 +106,15 @@ export class ApiClient {
       /** DELETE /api/delivery/{id} → 204 */
       delete: (id) => this.#empty('DELETE', `/api/delivery/${enc(id)}`),
       /**
-       * POST /api/delivery/parsePDF — multipart/form-data, field "pdf"
+       * POST /api/delivery/parse — multipart/form-data, field "file"
+       * Accepts PDF or text files (max 50 MB), detection via mimetype/filename
        * Returns an async generator that yields SSE event objects:
        *   { event: 'status'|'llm_call'|'tool_call'|'usage'|'progress'|'result'|'error', data: object }
        */
-      parsePdfSse: async function* (file) {
+      parseSse: async function* (file) {
         const formData = new FormData();
-        formData.append('pdf', file, file.name);
-        const res = await fetch('/api/delivery/parsePDF', {
+        formData.append('file', file, file.name);
+        const res = await fetch('/api/delivery/parse', {
           method: 'POST',
           credentials: 'include',
           body: formData,