feat(analytics): integrate AI/ML services — AVM endpoint, moderation pipeline, market index cron

- Add AiServiceClient HTTP client for Python FastAPI AI service with timeout and fallback
- Add HttpAVMService that calls Python AVM endpoint, falls back to PrismaAVMService on failure
- Add ListingCreatedModerationHandler: auto-flags suspicious listings via AI moderation on create
- Add MarketIndexCronService: daily cron job aggregating market stats per district/city/type
- Wire ScheduleModule and new providers into AnalyticsModule and AppModule
- Add unit tests for AiServiceClient, HttpAVMService, and moderation handler (all passing)

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

apps/api/src/modules/analytics/infrastructure/services/ai-service.client.ts

@@ -0,0 +1,108 @@
+import { Injectable, Logger } from '@nestjs/common';
+
+export interface AiPredictRequest {
+  area: number;
+  district: string;
+  city: string;
+  property_type: string;
+  bedrooms?: number;
+  bathrooms?: number;
+  floors?: number;
+  frontage?: number;
+  road_width?: number;
+  year_built?: number | null;
+  has_legal_paper?: boolean;
+}
+
+export interface AiPredictResponse {
+  estimated_price_vnd: number;
+  confidence: number;
+  price_per_m2: number;
+  price_range_low: number;
+  price_range_high: number;
+}
+
+export interface AiModerationRequest {
+  text: string;
+  context?: string;
+}
+
+export interface AiModerationFlag {
+  category: string;
+  severity: string;
+  matched_text: string;
+  reason: string;
+}
+
+export interface AiModerationResponse {
+  is_flagged: boolean;
+  score: number;
+  flags: AiModerationFlag[];
+  cleaned_text: string | null;
+}
+
+export const AI_SERVICE_CLIENT = Symbol('AI_SERVICE_CLIENT');
+
+export interface IAiServiceClient {
+  predict(req: AiPredictRequest): Promise<AiPredictResponse>;
+  moderate(req: AiModerationRequest): Promise<AiModerationResponse>;
+  isAvailable(): Promise<boolean>;
+}
+
+@Injectable()
+export class AiServiceClient implements IAiServiceClient {
+  private readonly logger = new Logger(AiServiceClient.name);
+  private readonly baseUrl: string;
+  private readonly apiKey: string;
+  private readonly timeoutMs: number;
+
+  constructor() {
+    this.baseUrl = process.env['AI_SERVICE_URL'] ?? 'http://localhost:8000';
+    this.apiKey = process.env['AI_SERVICE_API_KEY'] ?? '';
+    this.timeoutMs = Number(process.env['AI_SERVICE_TIMEOUT_MS']) || 5000;
+  }
+
+  async predict(req: AiPredictRequest): Promise<AiPredictResponse> {
+    return this.post<AiPredictResponse>('/avm/predict', req);
+  }
+
+  async moderate(req: AiModerationRequest): Promise<AiModerationResponse> {
+    return this.post<AiModerationResponse>('/moderation/check', req);
+  }
+
+  async isAvailable(): Promise<boolean> {
+    try {
+      const response = await fetch(`${this.baseUrl}/health`, {
+        method: 'GET',
+        signal: AbortSignal.timeout(2000),
+      });
+      return response.ok;
+    } catch {
+      return false;
+    }
+  }
+
+  private async post<T>(path: string, body: unknown): Promise<T> {
+    const url = `${this.baseUrl}${path}`;
+    const headers: Record<string, string> = {
+      'Content-Type': 'application/json',
+    };
+    if (this.apiKey) {
+      headers['X-API-Key'] = this.apiKey;
+    }
+
+    const response = await fetch(url, {
+      method: 'POST',
+      headers,
+      body: JSON.stringify(body),
+      signal: AbortSignal.timeout(this.timeoutMs),
+    });
+
+    if (!response.ok) {
+      const text = await response.text().catch(() => '');
+      throw new Error(`AI service ${path} returned ${response.status}: ${text}`);
+    }
+
+    return response.json() as Promise<T>;
+  }
+}