fix: pvc-autoresizer threshold should be 10%, not 80%

topolvm/pvc-autoresizer's threshold annotation is the FREE-SPACE
percentage below which expansion fires (per upstream README). Setting
it to "80%" means "expand when free-space drops below 80%", i.e. as
soon as the PVC crosses 20% utilization — which caused
prometheus-data-proxmox to be repeatedly expanded from 200Gi to 433Gi
in 70 minutes (six 10% bumps, all when the volume was only ~14% used).
Once the SC opt-in fix landed (1e4eac53) and the inode metrics fix
landed (02a12f1a), the autoresizer started actively misfiring across
75+ PVCs cluster-wide.

Flip the value to "10%" everywhere — that's "expand when free-space
drops below 10%", i.e. at 90% utilization, which is the conventional
semantic and matches the alert thresholds in
prometheus_chart_values.tpl (PVAutoExpanding fires at 80%, PVFillingUp
at 95%).

The CLAUDE.md PVC template was the source of the misconfig, so update
it too. Live PVC annotations were patched in parallel via kubectl
annotate; TF apply on each affected stack will be a no-op against
those live values.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

stacks/hackmd/main.tf

@@ -30,7 +30,7 @@ resource "kubernetes_persistent_volume_claim" "data_encrypted" {
     name      = "hackmd-data-encrypted"
     namespace = kubernetes_namespace.hackmd.metadata[0].name
     annotations = {
-      "resize.topolvm.io/threshold"     = "80%"
+      "resize.topolvm.io/threshold"     = "10%"
       "resize.topolvm.io/increase"      = "100%"
       "resize.topolvm.io/storage_limit" = "5Gi"
     }