feat(analytics): add GET /analytics/market-history endpoint

Time-series endpoint returning monthly/weekly market data points
for the analytics page. Queries MarketIndex aggregated by period
with 6-hour Redis cache. Includes unit tests.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/analytics/infrastructure/repositories/prisma-market-index.repository.ts

@@ -8,6 +8,7 @@ import {
   type HeatmapDataPoint,
   type PriceTrendPoint,
   type DistrictStatsResult,
+  type MarketHistoryPoint,
 } from '../../domain/repositories/market-index.repository';
 
 @Injectable()
@@ -173,6 +174,53 @@ export class PrismaMarketIndexRepository implements IMarketIndexRepository {
     }));
   }
 
+  async getMarketHistory(city: string, periods: string[]): Promise<MarketHistoryPoint[]> {
+    const records = await this.prisma.marketIndex.findMany({
+      where: {
+        city: { equals: city, mode: 'insensitive' },
+        period: { in: periods },
+      },
+      orderBy: { period: 'asc' },
+    });
+
+    // Aggregate across all districts/property types per period
+    const periodMap = new Map<string, {
+      totalAvgPrice: number;
+      totalMedian: bigint;
+      totalListings: number;
+      totalDaysOnMarket: number;
+      count: number;
+    }>();
+
+    for (const r of records) {
+      const existing = periodMap.get(r.period);
+      if (existing) {
+        existing.totalAvgPrice += r.avgPriceM2;
+        existing.totalMedian += r.medianPrice;
+        existing.totalListings += r.totalListings;
+        existing.totalDaysOnMarket += r.daysOnMarket;
+        existing.count++;
+      } else {
+        periodMap.set(r.period, {
+          totalAvgPrice: r.avgPriceM2,
+          totalMedian: r.medianPrice,
+          totalListings: r.totalListings,
+          totalDaysOnMarket: r.daysOnMarket,
+          count: 1,
+        });
+      }
+    }
+
+    return Array.from(periodMap.entries()).map(([period, data]) => ({
+      date: period,
+      avgPrice: Math.round(data.totalAvgPrice / data.count),
+      medianPrice: (data.totalMedian / BigInt(data.count)).toString(),
+      listingsCount: data.totalListings,
+      inquiriesCount: 0, // inquiries not tracked in MarketIndex
+      daysOnMarket: Math.round(data.totalDaysOnMarket / data.count),
+    }));
+  }
+
   private toDomain(raw: PrismaMarketIndex): MarketIndexEntity {
     const props: MarketIndexProps = {
       district: raw.district,