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/pages/demand/Results.tsx

@@ -12,7 +12,7 @@ import {
   ResultFilterBar,
   UnifiedResultFeed,
 } from '../../components/results'
-import { AddToShortlistDialog } from '../../components/shortlist'
+import { AddToPipelineDialog } from '../../components/shortlist'
 import { useSessionStore } from '../../stores/sessionStore'
 import type { ResultType } from '../../domain/enums'
 import type { UnifiedMatchResult } from '../../domain/unifiedResult'
@@ -91,7 +91,7 @@ export default function Results() {
 
   return (
     <Box sx={{ display: 'flex', flexDirection: 'column', height: '100%', overflow: 'hidden' }}>
-      <AddToShortlistDialog />
+      <AddToPipelineDialog />
       <ResultFeedHeader
         total={sorted.length}
         verifiedCount={verifiedCount}