feat: unit-level matching architecture — match against Einheiten, not Objekte

- domain/property: add getEffectiveUnits() — returns explicit units or synthesises
  one from property-level data so all properties work uniformly at unit level
- domain/match: add unitId? field — every Match references a specific unit
- domain/unifiedResult: add unit? to VerifiedPortfolioResult + ExternalMarketResult
- MockupNeedProvider: generateSyntheticMatches iterates getEffectiveUnits(prop);
  computeScore uses unit-level areaSqm + rentPricePerSqm; resultId for PRE-MARKET
  signals matches useSchattenmarktSignals signal ID format
- useUnifiedResults: resolve unit from match.unitId for VERIFIED_PORTFOLIO/EXTERNAL_MARKET
- matchCardAdapter: unit now extracted for all result types; unitId from match.unitId
- IntelligenceMatchCard: regular cards show unit chip (floor + label + m²) when a
  named unit is known — only adds context, never shows for synthetic/whole-property units

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

src/domain/match.ts

@@ -88,6 +88,7 @@ export interface Match {
   resultId?: string      // preferred: generic result ID
   resultType?: ResultType
   propertyId: string     // legacy alias for resultId (VERIFIED_PORTFOLIO)
+  unitId?: string        // specific rentable unit this match refers to
 
   // Scoring
   matchScore: number     // 0–100