feat(demand): market rent estimate (asking vs. fair) + pre-market expected price

- lib/rentEstimate: deterministic market estimate from Standort-Intelligence (median rent benchmark + vacancy/trend) → fair rent, verdict BELOW/AT/ABOVE, deltaPct, rationale; suggestFutureRent indexes today's price by city rent trend
- MarketPricePanel in MatchDetail: asking vs. fair market rent + verdict badge + rationale; shows pre-market expected price (heute → erwartet)
- unit.expectedRentPerSqm: future pre-market price; scorer prefers it over current rent for FUTURE_AVAILABILITY
- UnitStructurePanel editor: expected-price field (with indexed suggestion) shown for pre-market-released units
- tests: rentEstimate verdict thresholds + future-rent indexing

Note: rent estimate is a deterministic market-data calc (not an LLM) — honest & testable; can be routed through IAIService later if a real model is wanted.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/domain/unit.ts

@@ -24,6 +24,7 @@ export interface PropertyUnit {
   fitOutByLandlord?: boolean          // wer trägt den Ausbau (Default: Objekt-Wert)
   mieterausbaubeitragPerSqm?: number  // MAB der Einheit (Default: Objekt-Wert)
   parkingSpots?: number               // aus dem Objekt-Pool zugeteilte Parkplätze
+  expectedRentPerSqm?: number         // erwarteter künftiger Preis (Pre-Market), ≠ heutige Sollmiete
   leases?: Lease[]          // Mietverträge — current, historical, future
   /** @deprecated Use leases[].tenant.companyName */
   currentTenant?: string