refactor: merge nav — rename to Inserate, remove Neues Inserat sidebar entry

New listings are created via the button on the Inserate page, not as a
first-class nav destination.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/layout/appShellConfig.ts

@@ -13,7 +13,6 @@ import {
   MessageSquare,
   Kanban,
   BellRing,
-  Plus,
 } from 'lucide-react'
 
 // ---------------------------------------------------------------------------
@@ -54,8 +53,7 @@ export const WORKSPACE_CONFIG: Record<WorkspaceType, WorkspaceConfig> = {
       { path: '/supply/anfragen', label: 'Anfragencenter', icon: MessageSquare },
       { path: '/supply/data-quality', label: 'Datenpflege', icon: CheckSquare },
       { path: '/supply/market-intelligence', label: 'Markt Intelligence', icon: Radar },
-      { path: '/supply/my-listings', label: 'Meine Inserate', icon: ClipboardList },
+      { path: '/supply/my-listings', label: 'Inserate', icon: ClipboardList },
-      { path: '/supply/new-listing', label: 'Neues Inserat', icon: Plus },
     ],
   },
   [WorkspaceType.DEMAND]: {

src/pages/supply/MyListings.tsx

@@ -71,7 +71,7 @@ export default function MyListings() {
     <Box sx={{ maxWidth: 960, mx: 'auto', px: 3, py: 4 }}>
       <Box sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', mb: 3 }}>
         <Box>
-          <Typography variant="h5" sx={{ fontWeight: 700 }}>Meine Inserate</Typography>
+          <Typography variant="h5" sx={{ fontWeight: 700 }}>Inserate</Typography>
           <Typography variant="body2" color="text.secondary">
             Direkt erstellte Inserate — unabhängig vom Portfolio
           </Typography>