Initial: Prometheus + Grafana monitoring stack

- Prometheus with 9 scrape targets
- Grafana with Home Server Overview dashboard
- Exporters: node_exporter, cadvisor, postgres_exporter (x3), qbittorrent
- Traefik and Gitea metrics enabled

prometheus.yml

@@ -0,0 +1,40 @@
+global:
+  scrape_interval: 15s
+  evaluation_interval: 15s
+
+scrape_configs:
+  - job_name: prometheus
+    static_configs:
+      - targets: ['localhost:9090']
+
+  - job_name: traefik
+    static_configs:
+      - targets: ['traefik:8080']
+
+  - job_name: gitea
+    static_configs:
+      - targets: ['gitea:3000']
+
+  - job_name: node
+    static_configs:
+      - targets: ['node_exporter:9100']
+
+  - job_name: cadvisor
+    static_configs:
+      - targets: ['cadvisor:8081']
+
+  - job_name: postgres_pgvector
+    static_configs:
+      - targets: ['postgres_exporter_pgvector:9187']
+
+  - job_name: postgres_langfuse
+    static_configs:
+      - targets: ['postgres_exporter_langfuse:9188']
+
+  - job_name: postgres_mcpjungle
+    static_configs:
+      - targets: ['postgres_exporter_mcpjungle:9189']
+
+  - job_name: qbittorrent
+    static_configs:
+      - targets: ['qbittorrent_exporter:8000']