k8s/monitoring: add prometheus grafana loki observability

- Loki log aggregation (MinIO backed, 10-day retention)
- Promtail daemonset (pod + talos journal logs)
- Prometheus + kube-state-metrics
- Grafana dashboards (6-row template per service)

k8s/monitoring/dashboards/services/story-crater-frontend.descriptor.yaml

@@ -0,0 +1,63 @@
+# story-crater-frontend.descriptor.yaml
+# Build input for generating svc-story-crater-frontend.yaml dashboard ConfigMap
+# and svc-story-crater-frontend-rules.yaml PrometheusRule.
+# NOT applied to cluster — this is a reference for Claude's mechanical dashboard generation.
+
+service: story-crater-frontend
+display_name: "Story Crater Frontend"
+namespace: story-crater-frontend
+service_type: web-app
+folder: "Story Crater Frontend"
+
+jobs:
+  - story-crater-frontend
+
+metrics:
+  prefix: story_crater_frontend
+  up_selector: 'job="story-crater-frontend"'
+
+  rate:
+    metric: story_crater_frontend_http_requests_total
+    labels: [method, route, status]
+
+  duration:
+    metric: story_crater_frontend_http_request_duration_ms
+    type: histogram
+    unit: ms
+
+  error:
+    metric: story_crater_frontend_http_requests_total
+    filter: 'status=~"5.."'
+
+  domain:
+    - metric: story_crater_frontend_web_vitals_lcp_ms
+      kind: gauge
+      group_by: [page]
+    - metric: story_crater_frontend_web_vitals_fid_ms
+      kind: gauge
+      group_by: [page]
+    - metric: story_crater_frontend_web_vitals_cls
+      kind: gauge
+      group_by: [page]
+    - metric: story_crater_frontend_web_vitals_inp_ms
+      kind: gauge
+      group_by: [page]
+
+correlation_ids: []  # Frontend doesn't have session_id/trace_id in metrics
+
+logs:
+  loki_namespace_selector: 'namespace="story-crater-frontend"'
+
+alerts:
+  - name: HighErrorRate
+    expr_template: rate_error_ratio
+    threshold: 0.05
+    for: 10m
+    severity: warning
+  - name: WebVitalsLCPRegression
+    expr_template: histogram_quantile_over_threshold
+    metric: story_crater_frontend_web_vitals_lcp_ms
+    quantile: 0.75
+    threshold: 2500
+    for: 10m
+    severity: warning