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/domain/pipeline.ts

@@ -7,6 +7,8 @@ export interface PipelineItem {
   matchScore: number
   resultType: 'VERIFIED_PORTFOLIO' | 'EXTERNAL_MARKET' | 'MAISON_WORK' | 'FUTURE_AVAILABILITY'
   stage: PipelineStage
+  // Source match reference — used for navigating back to the detail page
+  matchId?: string
   // Property / unit reference — always set for unit-level tracking
   propertyId?: string
   unitId?: string