fix: Compare→Pipeline flow, pipeline card navigation, remove floating AI button

- Remove CompareTray fixed bottom bar; replace with compare count badge on Vergleich nav item
- Pipeline cards redesigned to match search result card visual style (MatchScoreDisplay, type chip, stage chip, MapPin layout)
- CompareColumnHeader: redesigned with proper Details/Merken action buttons, clickable title
- AddToPipelineDialog now mounted on Compare page (was missing — bookmark had no effect)
- Pipeline card ExternalLink icon navigates to property detail page; detailPath prefers stable propertyId over volatile session matchId
- Add matchId field to PipelineItem domain; pipelineStore stores it on save
- All 8 mock pipeline items now have propertyId for reliable cross-session navigation
- Remove GlobalAIAssistantButton floating overlay (was blocking form submissions and clicks)

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

src/pages/demand/Compare.tsx

@@ -29,6 +29,7 @@ import {
   MissingDataCell,
   AICompareSummary,
 } from '../../components/compare'
+import { AddToPipelineDialog } from '../../components/shortlist'
 import type { UnifiedMatchResult } from '../../domain/unifiedResult'
 import type { VerifiedPortfolioResult, ExternalMarketResult, FutureAvailabilityResult } from '../../domain/unifiedResult'
 
@@ -204,6 +205,8 @@ export default function Compare() {
 
   return (
     <Box>
+      <AddToPipelineDialog />
+
       {/* Page header */}
       <Box sx={{ bgcolor: 'white', borderBottom: '1px solid #e2e8f0', px: 3, py: 2, display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
         <Box sx={{ display: 'flex', alignItems: 'center', gap: 2 }}>