feat(deploy): add Prometheus scrape config

deploy/truenas/core/prom/prometheus.yml

@@ -0,0 +1,19 @@
+global:
+  scrape_interval: 15s
+  scrape_timeout: 10s
+  evaluation_interval: 15s
+  external_labels:
+    core: dragonfork-truenas
+
+rule_files:
+  - /etc/prometheus/rules/*.yml
+
+scrape_configs:
+  - job_name: dragonfork-core
+    static_configs:
+      - targets: ["host.docker.internal:${CORE_HTTP_PORT:-8080}"]
+    metrics_path: /metrics
+    # If API auth is enabled on /metrics, uncomment and add creds:
+    # basic_auth:
+    #   username: <user>
+    #   password: <pass>