feat(ai): AI pre-market rent recommendation from regional comparables, supply & demand

- IAIService.recommendPreMarketRent: recommended price + range, verdict (UNDERPRICED/FAIR/AMBITIOUS), drivers, rationale, confidence
- MockAIService: deterministic recommendation from locationIntelligence — regional comp median, vacancy (supply), demand strength + days-on-market, rent trend (forward for pre-market)
- BackendAIService: LLM prompt with market context + mock fallback
- usePreMarketRentRecommendation hook; PreMarketPriceAdvisor component shows the recommendation per released unit with verdict ("zu günstig" when underpriced) + adjustable expected price + "Empfehlung übernehmen"
- Replaces the simple indexed suggestion with a market-driven AI recommendation that flags underpricing

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

src/hooks/useAI.ts

@@ -1,6 +1,6 @@
 import { useMutation, useQuery } from '@tanstack/react-query'
 import { aiService, parseListingText } from '../services/aiService'
-import type { OfferEmailPayload, FitOutAdviceInput } from '../services/aiService'
+import type { OfferEmailPayload, FitOutAdviceInput, PreMarketRentInput } from '../services/aiService'
 
 export function useParseNeed() {
   return useMutation({
@@ -34,3 +34,12 @@ export function useFitOutAdvice(input: FitOutAdviceInput | null) {
     staleTime: Infinity,
   })
 }
+
+export function usePreMarketRentRecommendation(input: PreMarketRentInput | null) {
+  return useQuery({
+    queryKey: ['preMarketRent', input],
+    queryFn: () => aiService.recommendPreMarketRent(input!),
+    enabled: !!input && !!input.city,
+    staleTime: Infinity,
+  })
+}