feat: Objekt→Einheit architecture — unit-level pre-market, property detail page, click-through from cards

- Domain: PropertyUnit extended with propertyId + schattenmarktRelease per unit
- Domain: FutureAvailabilityResult carries resolved property + unit
- useSchattenmarktSignals: generates unit-level signals (schattenmarkt-{propId}-{unitId})
- useUnifiedResults: resolves backing property + unit on FUTURE_AVAILABILITY fast path
- IUnitProvider + MockupUnitProvider: first-class unit access and mutation
- matchCardAdapter: maps preMarketUnit, preMarketAllUnits, propertyId, unitId to ViewModel
- IntelligenceMatchCard: PRE-MARKET VERIFIED shows unit info strip + "Zur Einheit →" button
- PropertyDetailView: unit-level toggles + date pickers inside PreMarketPanel
- New page: /demand/property/:propertyId with unit table, status chips, inquiry form
- App.tsx: demand route /demand/property/:propertyId registered
- Mock data: prop-001/007/037 units updated with correct lease dates + unit-level schattenmarktRelease

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

src/domain/unifiedResult.ts

@@ -1,5 +1,5 @@
 import type { ResultType } from './enums'
-import type { Property } from './property'
+import type { Property, PropertyUnit } from './property'
 import type { FutureSignal } from './futureSignal'
 import type { Match } from './match'
 
@@ -30,6 +30,8 @@ export interface FutureAvailabilityResult extends UnifiedResultBase {
   resultType: 'FUTURE_AVAILABILITY'
   signal: FutureSignal
   match: Match
+  property?: Property           // backing property (when signal has a propertyId)
+  unit?: PropertyUnit           // specific rentable unit (when signal has a unitId)
 }
 
 export type UnifiedMatchResult =