feat: add ServiceMonitors and enable metrics scraping

- SeaweedFS: enable -metricsPort=9091 on master/volume/filer, add
  service labels, create ServiceMonitor
- Gitea: enable metrics in config, create ServiceMonitor
- Hydra/Kratos: standalone ServiceMonitors (chart templates require
  .Capabilities.APIVersions unavailable in kustomize helm template)
- LiveKit: add prometheus_port=6789, standalone ServiceMonitor
  (disabled in kustomization — host firewall blocks port 6789)
- OpenSearch: revert prometheus-exporter attempt (no plugin for v3.x),
  add service label for future exporter sidecar

base/storage/seaweedfs-master.yaml

@@ -23,6 +23,7 @@ spec:
             - -mdir=/data
             - -defaultReplication=000
             - -volumeSizeLimitMB=1000
+            - -metricsPort=9091
           ports:
             - name: http
               containerPort: 9333
@@ -30,6 +31,9 @@ spec:
             - name: grpc
               containerPort: 19333
               protocol: TCP
+            - name: metrics
+              containerPort: 9091
+              protocol: TCP
           volumeMounts:
             - name: data
               mountPath: /data
@@ -53,6 +57,8 @@ kind: Service
 metadata:
   name: seaweedfs-master
   namespace: storage
+  labels:
+    app: seaweedfs-master
 spec:
   selector:
     app: seaweedfs-master
@@ -64,3 +70,6 @@ spec:
     - name: grpc
       port: 19333
       targetPort: 19333
+    - name: metrics
+      port: 9091
+      targetPort: 9091