feat(storage): migrate all sensitive services to proxmox-lvm-encrypted

Reconcile Terraform with cluster state after manual encrypted PVC migrations
and complete the remaining unfinished migrations. All services storing
sensitive data now use LUKS2-encrypted block storage via the Proxmox CSI
plugin.

## Context

Only Technitium DNS was using encrypted storage in Terraform. Many services
had been manually migrated to encrypted PVCs in the cluster, but Terraform
was never updated — creating dangerous state drift where a `tg apply` could
recreate unencrypted PVCs.

## This change

Phase 0 — Infrastructure:
- Add `proxmox-lvm-encrypted` StorageClass to Helm values (extraParameters)
- Add ExternalSecret for LUKS encryption passphrase to Terraform
- Fix CSI node plugin memory: `node.plugin.resources` (not `node.resources`)
  with 1280Mi limit for LUKS2 Argon2id key derivation

Phase 1 — TF state reconciliation (zero downtime):
- Health, Matrix, N8N, Forgejo, Vaultwarden, Mailserver: state rm + import
- Redis, DBAAS MySQL, DBAAS PostgreSQL: Helm/CNPG value updates

Phase 2 — Data migration (encrypted PVCs existed but unused):
- Headscale, Frigate, MeshCentral: rsync + switchover
- Nextcloud (20Gi): rsync + chart_values update

Phase 3 — New encrypted PVCs:
- Roundcube HTML, HackMD, Affine, DBAAS pgadmin: create + rsync + switchover

Phase 4 — Cleanup:
- Deleted 5 orphaned unencrypted PVCs

## Services migrated (18 PVCs across 14 namespaces)

```
vaultwarden     → vaultwarden-data-encrypted
dbaas           → datadir-mysql-cluster-0, pg-cluster-{1,2}, dbaas-pgadmin-encrypted
mailserver      → mailserver-data-encrypted, roundcubemail-{enigma,html}-encrypted
nextcloud       → nextcloud-data-encrypted
forgejo         → forgejo-data-encrypted
matrix          → matrix-data-encrypted
n8n             → n8n-data-encrypted
affine          → affine-data-encrypted
health          → health-uploads-encrypted
hackmd          → hackmd-data-encrypted
redis           → redis-data-redis-node-{0,1}
headscale       → headscale-data-encrypted
frigate         → frigate-config-encrypted
meshcentral     → meshcentral-{data,files}-encrypted
```

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

stacks/hackmd/main.tf

@@ -20,10 +20,10 @@ module "tls_secret" {
   tls_secret_name = var.tls_secret_name
 }
 
-resource "kubernetes_persistent_volume_claim" "data_proxmox" {
+resource "kubernetes_persistent_volume_claim" "data_encrypted" {
   wait_until_bound = false
   metadata {
-    name      = "hackmd-data-proxmox"
+    name      = "hackmd-data-encrypted"
     namespace = kubernetes_namespace.hackmd.metadata[0].name
     annotations = {
       "resize.topolvm.io/threshold"     = "80%"
@@ -33,7 +33,7 @@ resource "kubernetes_persistent_volume_claim" "data_proxmox" {
   }
   spec {
     access_modes       = ["ReadWriteOnce"]
-    storage_class_name = "proxmox-lvm"
+    storage_class_name = "proxmox-lvm-encrypted"
     resources {
       requests = {
         storage = "1Gi"
@@ -154,7 +154,7 @@ resource "kubernetes_deployment" "hackmd" {
         volume {
           name = "data"
           persistent_volume_claim {
-            claim_name = kubernetes_persistent_volume_claim.data_proxmox.metadata[0].name
+            claim_name = kubernetes_persistent_volume_claim.data_encrypted.metadata[0].name
           }
         }
       }