fix(infra): resolve NestJS dist build and Prometheus target issues

NestJS: disable incremental in 6 services tsconfig.json to fix dist
not emitted when nest-cli deleteOutDir conflicts with tsc tsbuildinfo.
classes/iam: import HealthModule in AppModule to fix /healthz 404.
classes: rewrite HealthController to Drizzle getDb from TypeORM DI.
teacher-bff: add /metrics endpoint for Prometheus scraping.
infra: add node/mysql/redis exporters to observability profile.
mysql-exporter v0.15.1 uses command-line flags not DATA_SOURCE_NAME.
prometheus: enable web.enable-lifecycle for hot reload.

infra/docker-compose.yml

@@ -184,8 +184,14 @@ services:
     container_name: edu-prometheus
     profiles: ["observability"]
     restart: unless-stopped
+    command:
+      - "--config.file=/etc/prometheus/prometheus.yml"
+      - "--storage.tsdb.path=/prometheus"
+      - "--storage.tsdb.retention.time=15d"
+      - "--web.enable-lifecycle"
     volumes:
       - ./prometheus.yml:/etc/prometheus/prometheus.yml:ro
+      - prometheus_data:/prometheus
     ports:
       - "9090:9090"
   grafana:
@@ -199,6 +205,49 @@ services:
       - "3030:3000"
     volumes:
       - grafana_data:/var/lib/grafana
+  # ============================================================
+  # Exporters（observability profile，与 Prometheus 同网络）
+  # ============================================================
+  node-exporter:
+    image: docker.m.daocloud.io/prom/node-exporter:v1.8.2
+    container_name: edu-node-exporter
+    profiles: ["observability"]
+    restart: unless-stopped
+    command:
+      - "--path.rootfs=/host"
+    ports:
+      - "9100:9100"
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/host:ro
+  mysql-exporter:
+    image: docker.m.daocloud.io/prom/mysqld-exporter:v0.15.1
+    container_name: edu-mysql-exporter
+    profiles: ["observability"]
+    restart: unless-stopped
+    command:
+      - "--mysqld.address=edu-mysql:3306"
+      - "--mysqld.username=edu:changeme"
+    environment:
+      MYSQLD_EXPORTER_PASSWORD: "changeme"
+    ports:
+      - "9104:9104"
+    depends_on:
+      mysql:
+        condition: service_healthy
+  redis-exporter:
+    image: docker.m.daocloud.io/oliver006/redis_exporter:v1.67.0
+    container_name: edu-redis-exporter
+    profiles: ["observability"]
+    restart: unless-stopped
+    environment:
+      REDIS_ADDR: "redis://edu-redis:6379"
+    ports:
+      - "9121:9121"
+    depends_on:
+      redis:
+        condition: service_started
 volumes:
   mysql_data:
   redis_data:
@@ -206,3 +255,4 @@ volumes:
   neo4j_data:
   es_data:
   grafana_data:
+  prometheus_data:

infra/prometheus.yml

@@ -89,6 +89,6 @@ scrape_configs:
 
   - job_name: 'node-exporter'
     static_configs:
-      - targets: ['node-exporter:9100']
+      - targets: ['host.docker.internal:9100']
         labels:
           service: node-exporter