feat(monitoring): add Prometheus metrics endpoint and Grafana dashboards

Add observability stack with @willsoto/nestjs-prometheus for /metrics endpoint,
Prometheus scraping config, and 4 auto-provisioned Grafana dashboards
(API overview, database, search, business metrics).

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

monitoring/grafana/provisioning/dashboards/dashboard.yml

@@ -0,0 +1,12 @@
+apiVersion: 1
+
+providers:
+  - name: 'GoodGo Dashboards'
+    orgId: 1
+    folder: 'GoodGo'
+    type: file
+    disableDeletion: false
+    editable: true
+    options:
+      path: /var/lib/grafana/dashboards
+      foldersFromFilesStructure: false

monitoring/grafana/provisioning/datasources/datasource.yml

@@ -0,0 +1,9 @@
+apiVersion: 1
+
+datasources:
+  - name: Prometheus
+    type: prometheus
+    access: proxy
+    url: http://prometheus:9090
+    isDefault: true
+    editable: true