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/new-listing', label: 'Neues Inserat', icon: Plus },
+      { path: '/supply/my-listings', label: 'Inserate', icon: ClipboardList },
     ],
   },
   [WorkspaceType.DEMAND]: {