Grafana: startup probe so a slow first start is not killed

Grafana's first start creates and migrates its database: 44 s at
0.5 CPU and 3 minutes at 0.1 CPU (measured with 13.2.3 on an empty
volume). With only 50m requested, the liveness probe (30 s delay,
3 x 30 s) restarted it mid-migration, in a loop, and readiness never
passed.

- startupProbe on /api/health allows up to 10 minutes; liveness and
  readiness start only after it succeeds.
- 5 s timeouts on all probes instead of the 1 s default.
- Requests raised to 250m CPU / 256Mi (measured about 240 MB in use);
  still no CPU limit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki

k8s/grafana.yaml

@@ -85,21 +85,34 @@ spec:
               mountPath: /etc/grafana/provisioning/dashboards
             - name: dashboards
               mountPath: /var/lib/grafana/dashboards/mg4
+          # The first start creates and migrates Grafana's database: measured 44 s at 0.5 CPU
+          # and 3 minutes at 0.1 CPU. The startup probe allows up to 10 minutes for that, and
+          # liveness/readiness only begin once it succeeded, so a slow first start is never
+          # killed mid-migration (which would restart it slowly again, in a loop).
+          startupProbe:
+            httpGet:
+              path: /api/health
+              port: http
+            periodSeconds: 10
+            timeoutSeconds: 5
+            failureThreshold: 60
           readinessProbe:
             httpGet:
               path: /api/health
               port: http
             periodSeconds: 10
+            timeoutSeconds: 5
           livenessProbe:
             httpGet:
               path: /api/health
               port: http
-            initialDelaySeconds: 30
             periodSeconds: 30
+            timeoutSeconds: 5
+            failureThreshold: 3
           resources:
             requests:
-              cpu: 50m
-              memory: 128Mi
+              cpu: 250m
+              memory: 256Mi
             limits:
               memory: 512Mi
           securityContext: