Directly patch posterminalIds in Redux instead of reloading the category tree

After toggling a POS category, update the category's posterminalIds array
in-place rather than re-fetching the entire tree. This keeps the settings
cycle open on the same terminal. Also fix off-by-one in terminal cycling
and ensure posterminals load on category page mount.

src/pages/artikel/kategorien.jsx

@@ -21,7 +21,7 @@ import {
 import withCategoryRoute from './withCategoryRoute';
 import { artikelDetailPath, articleSku } from './articleRoute';
 import { selectCompanyId } from '../../store/companySlice';
-import { selectHasPosterminals, selectPosterminals } from '../../store/posterminalSlice';
+import { selectHasPosterminals, selectPosterminals, loadPosterminals } from '../../store/posterminalSlice';
 import {
   buildCategoryPath,
   defaultCategoryPath,
@@ -47,6 +47,7 @@ import {
   selectCategoryTreeStatus,
   selectChildCategories,
   selectRenameMode,
+  patchCategoryPosterminalIds,
 } from '../../store/categorySlice';
 import {
   enableTerminalCategory,
@@ -72,6 +73,7 @@ class ArtikelKategorienPage extends Component {
 
   componentDidMount() {
     this.ensureTreeLoaded();
+    this.ensurePosterminalsLoaded();
     this.syncCategoryFromUrl();
     this.ensureArticlesLoaded();
     this.syncSortable();
@@ -158,6 +160,12 @@ class ArtikelKategorienPage extends Component {
     this.props.loadCategoryTree();
   };
 
+  ensurePosterminalsLoaded = () => {
+    const { companyId } = this.props;
+    if (!companyId) return;
+    this.props.loadPosterminals();
+  };
+
   ensureArticlesLoaded = () => {
     const { currentCategoryId, articlesStatus, rootCategoryId, treeStatus } = this.props;
     if (treeStatus !== 'succeeded' || !currentCategoryId || articlesStatus !== 'idle') return;
@@ -356,7 +364,13 @@ class ArtikelKategorienPage extends Component {
                       : this.props.disableTerminalCategory;
                     void thunk({ terminalId, categoryId: item.id })
                       .unwrap()
-                      .then(() => this.props.loadCategoryTree())
+                      .then(() => {
+                        this.props.patchCategoryPosterminalIds({
+                          categoryId: item.id,
+                          terminalId,
+                          enabled,
+                        });
+                      })
                       .catch(notifyError);
                   }}
                   onOpen={() => this.navigateToCategoryById(item.id)}
@@ -456,6 +470,7 @@ const mapStateToProps = (state) => ({
 const mapDispatchToProps = {
   loadCategoryTree,
   loadCategoryArticles,
+  loadPosterminals,
   navigateToCategory,
   renameCategory,
   deleteCategory,
@@ -464,6 +479,7 @@ const mapDispatchToProps = {
   toggleCategoryPos,
   enableTerminalCategory,
   disableTerminalCategory,
+  patchCategoryPosterminalIds,
 };
 
 export default withCategoryRoute(connect(mapStateToProps, mapDispatchToProps)(ArtikelKategorienPage));