stabilize Nextcloud: relax probes, reduce resources for 2-client SQLite workload

SQLite locks cause slow responses under concurrent access, triggering
liveness probe failures and restarts. With only 2 sync clients:

- Liveness: period 30→60s, timeout 10→30s, failures 6→10 (tolerates 10min)
- Readiness: period 30→60s, timeout 10→30s, failures 3→5
- Startup: timeout 10→30s
- Resources: CPU 16→4, memory 6Gi→3Gi (10 workers × 200MB = 2GB max)

[ci skip]

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

stacks/nextcloud/chart_values.yaml

@@ -67,24 +67,24 @@ startupProbe:
   enabled: true
   initialDelaySeconds: 30
   periodSeconds: 10
-  timeoutSeconds: 10
+  timeoutSeconds: 30
   failureThreshold: 60
   successThreshold: 1
 
 livenessProbe:
   enabled: true
-  initialDelaySeconds: 10
+  initialDelaySeconds: 30
-  periodSeconds: 30
+  periodSeconds: 60
-  timeoutSeconds: 10
+  timeoutSeconds: 30
-  failureThreshold: 6
+  failureThreshold: 10
   successThreshold: 1
 
 readinessProbe:
   enabled: true
-  initialDelaySeconds: 10
+  initialDelaySeconds: 30
-  periodSeconds: 30
+  periodSeconds: 60
-  timeoutSeconds: 10
+  timeoutSeconds: 30
-  failureThreshold: 3
+  failureThreshold: 5
   successThreshold: 1
 
 podAnnotations:
@@ -96,11 +96,11 @@ collabora:
 
 resources:
   limits:
-    cpu: "16"
+    cpu: "4"
-    memory: 6Gi
+    memory: 3Gi
   requests:
     cpu: 100m
-    memory: 1Gi
+    memory: 512Mi
 
 cronjob:
   enabled: true