feat: merge Merkliste into Pipeline (SAVED stage) + Anfragen chat page

- Remove standalone Merkliste/Shortlists nav item; pipeline now covers the full funnel
- Add SAVED as first PipelineStage — 'Merken' on result cards lands here
- pipelineStore (Zustand) holds shared items; AddToPipelineDialog replaces AddToShortlistDialog in demand workspace
- New /demand/anfragen split-panel: searchable inquiry list + chat thread with compose
- Pipeline detail panel: KI insight, stage actions, editable notes, mock documents
- ShortlistItemCard: cards clickable → property detail, Anfrage button with inline dialog
- Supply workspace (FutureAvailability, Anfragencenter) unchanged

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

src/components/layout/AppShell.tsx

@@ -103,7 +103,7 @@ const WORKSPACE_CONFIG: Record<WorkspaceType, WorkspaceConfig> = {
       { path: '/demand/ai-search', label: 'Flächensuche', icon: Search },
       { path: '/demand/results', label: 'Ergebnisse', icon: List },
       { path: '/demand/compare', label: 'Vergleich', icon: Columns2 },
-      { path: '/demand/shortlists', label: 'Shortlists', icon: Bookmark },
+      { path: '/demand/anfragen', label: 'Anfragen', icon: MessageSquare },
       { path: '/demand/pipeline', label: 'Deal Pipeline', icon: Kanban },
     ],
   },
@@ -134,6 +134,7 @@ function getPageNameFromPath(pathname: string): string {
   if (/^\/demand\/results\/.+/.test(pathname)) return 'Match Detail'
   if (/^\/demand\/property\//.test(pathname)) return 'Objekt Detail'
   if (/^\/supply\/properties\/.+/.test(pathname)) return 'Objekt Detail'
+  if (pathname === '/demand/anfragen') return 'Anfragen'
   const segment = pathname.split('/').filter(Boolean).pop() ?? ''
   return segment.charAt(0).toUpperCase() + segment.slice(1).replace(/-/g, ' ')
 }