ingress latency: add histogram buckets, fix restarts, right-size memory

- Traefik: add fine-grained Prometheus histogram buckets (0.01-30s) for meaningful P50/P99
- Calibre: relax liveness probe (timeout 5→10s, threshold 3→6) to stop NFS-caused restarts
- Novelapp: increase memory 128Mi/256Mi → 640Mi/640Mi (confirmed OOMKilled, VPA upper 505Mi)
- Forgejo: increase memory 256Mi → 384Mi (at 80% of limit, VPA upper 311Mi)
- ActualBudget: add explicit resources to prevent silent LimitRange defaults
- Docs: update Nextcloud note from 4Gi → 8Gi limit (Apache spike history)

stacks/traefik/modules/traefik/main.tf

@@ -172,6 +172,7 @@ resource "helm_release" "traefik" {
         addEntryPointsLabels = true
         addServicesLabels    = true
         addRoutersLabels     = true
+        buckets              = "0.01,0.05,0.1,0.2,0.5,1.0,2.0,5.0,10.0,30.0"
       }
     }