feat: all 4 UX priorities — wizard, examples, onboarding, pipeline

- Offer wizard: 4→3 steps by merging 'Prüfen' into PDF review step
- Search mask: quick-select chips for area ranges, budget, and city presets
- Onboarding: WelcomeDialog (3 slides, localStorage) on first visit
- Deal Pipeline: Kanban board (6 stages, 8 mock items, advance-to-next-stage)
  added to demand workspace navigation

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

src/domain/pipeline.ts

@@ -0,0 +1,17 @@
+export type PipelineStage = 'DISCOVERED' | 'QUALIFIED' | 'VISITED' | 'NEGOTIATION' | 'CLOSED_WON' | 'CLOSED_LOST'
+
+export interface PipelineItem {
+  id: string
+  title: string
+  location: string
+  matchScore: number
+  resultType: 'VERIFIED_PORTFOLIO' | 'EXTERNAL_MARKET' | 'FUTURE_AVAILABILITY'
+  stage: PipelineStage
+  areaLabel?: string
+  rentLabel?: string
+  availabilityLabel?: string
+  addedAt: string
+  updatedAt: string
+  notes?: string
+  assignedTo?: string
+}