Refactor navigation structure to enhance language learning features

- Renamed 'vocabtrainer' to 'sprachenlernen' in the navigation structure for better clarity.
- Introduced a nested structure under 'sprachenlernen' for 'vocabtrainer' and 'sprachkurse', improving organization of language-related resources.
- Updated internationalization files for both German and English to reflect the new naming and structure, ensuring consistency across the application.

backend/controllers/navigationController.js

@@ -50,10 +50,19 @@ const menuStructure = {
                 visible: ["all"],
                 path: "/socialnetwork/gallery"
             },
-            vocabtrainer: {
+            sprachenlernen: {
                 visible: ["all"],
-                path: "/socialnetwork/vocab",
-                children: {}
+                children: {
+                    vocabtrainer: {
+                        visible: ["all"],
+                        path: "/socialnetwork/vocab",
+                        children: {}
+                    },
+                    sprachkurse: {
+                        visible: ["all"],
+                        path: "/socialnetwork/vocab/courses"
+                    }
+                }
             },
             blockedUsers: {
                 visible: ["all"],
@@ -377,9 +386,9 @@ class NavigationController {
             const rights = userRights.map(ur => ur.rightType?.title).filter(Boolean);
             const filteredMenu = await this.filterMenu(menuStructure, rights, age, user.id);
 
-            // Dynamisches Submenü: Treffpunkt → Vokabeltrainer → (Neue Sprache + abonnierte/angelegte)
+            // Dynamisches Submenü: Treffpunkt → Sprachen lernen → Vokabeltrainer → (Neue Sprache + abonnierte/angelegte)
             // Wichtig: "Neue Sprache" soll IMMER sichtbar sein – auch wenn die DB-Abfrage (noch) fehlschlägt.
-            if (filteredMenu?.socialnetwork?.children?.vocabtrainer) {
+            if (filteredMenu?.socialnetwork?.children?.sprachenlernen?.children?.vocabtrainer) {
                 const children = {
                     newLanguage: { path: '/socialnetwork/vocab/new' },
                 };
@@ -391,7 +400,7 @@ class NavigationController {
                 } catch (e) {
                     console.warn('[menu] Konnte Vokabeltrainer-Sprachen nicht laden:', e?.message || e);
                 }
-                filteredMenu.socialnetwork.children.vocabtrainer.children = children;
+                filteredMenu.socialnetwork.children.sprachenlernen.children.vocabtrainer.children = children;
             }
 
             res.status(200).json(filteredMenu);