feat(metrics): add MetricsService, HttpMetricsInterceptor, and metric constants

- Extract metric names into constants with goodgo_ prefix for business metrics
- Add MetricsService for type-safe metric recording
- Add HttpMetricsInterceptor for automatic request duration/count tracking
- Register interceptor globally via APP_INTERCEPTOR
- Include linter auto-fixes for test files

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

apps/api/src/modules/metrics/metrics.module.ts

@@ -5,6 +5,19 @@ import {
   makeHistogramProvider,
   makeGaugeProvider,
 } from '@willsoto/nestjs-prometheus';
+import { MetricsService } from './infrastructure/metrics.service';
+import {
+  GOODGO_API_REQUEST_DURATION,
+  GOODGO_LISTINGS_CREATED_TOTAL,
+  GOODGO_PAYMENTS_PROCESSED_TOTAL,
+  GOODGO_ACTIVE_SUBSCRIPTIONS,
+  GOODGO_SEARCH_QUERIES_TOTAL,
+  HTTP_REQUESTS_TOTAL,
+  DB_QUERY_DURATION,
+  DB_POOL_ACTIVE_CONNECTIONS,
+  SEARCH_QUERY_DURATION,
+} from './metrics.constants';
+import { HttpMetricsInterceptor } from './presentation/interceptors/http-metrics.interceptor';
 
 @Module({
   imports: [
@@ -16,56 +29,63 @@ import {
   providers: [
     // ── HTTP Metrics ──
     makeHistogramProvider({
-      name: 'http_request_duration_seconds',
+      name: GOODGO_API_REQUEST_DURATION,
       help: 'Duration of HTTP requests in seconds',
       labelNames: ['method', 'route', 'status_code'],
       buckets: [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10],
     }),
     makeCounterProvider({
-      name: 'http_requests_total',
+      name: HTTP_REQUESTS_TOTAL,
       help: 'Total number of HTTP requests',
       labelNames: ['method', 'route', 'status_code'],
     }),
 
     // ── Database Metrics ──
     makeHistogramProvider({
-      name: 'db_query_duration_seconds',
+      name: DB_QUERY_DURATION,
       help: 'Duration of database queries in seconds',
       labelNames: ['operation', 'model'],
       buckets: [0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5],
     }),
     makeGaugeProvider({
-      name: 'db_pool_active_connections',
+      name: DB_POOL_ACTIVE_CONNECTIONS,
       help: 'Number of active database connections',
     }),
 
     // ── Search Metrics ──
     makeHistogramProvider({
-      name: 'search_query_duration_seconds',
+      name: SEARCH_QUERY_DURATION,
       help: 'Duration of search queries in seconds',
       labelNames: ['collection', 'type'],
       buckets: [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1],
     }),
-
-    // ── Cache Metrics ── (registered in SharedModule alongside CacheService)
+    makeCounterProvider({
+      name: GOODGO_SEARCH_QUERIES_TOTAL,
+      help: 'Total number of search queries',
+      labelNames: ['collection', 'type'],
+    }),
 
     // ── Business Metrics ──
     makeCounterProvider({
-      name: 'listings_created_total',
+      name: GOODGO_LISTINGS_CREATED_TOTAL,
       help: 'Total number of listings created',
       labelNames: ['category'],
     }),
     makeCounterProvider({
-      name: 'payments_processed_total',
+      name: GOODGO_PAYMENTS_PROCESSED_TOTAL,
       help: 'Total number of payments processed',
       labelNames: ['status', 'method'],
     }),
     makeGaugeProvider({
-      name: 'active_subscriptions',
+      name: GOODGO_ACTIVE_SUBSCRIPTIONS,
       help: 'Number of active subscriptions',
       labelNames: ['plan'],
     }),
+
+    // ── Services & Interceptors ──
+    MetricsService,
+    HttpMetricsInterceptor,
   ],
-  exports: [PrometheusModule],
+  exports: [PrometheusModule, MetricsService, HttpMetricsInterceptor],
 })
 export class MetricsModule {}