truenas deprecation: migrate all non-immich storage to proxmox NFS

- Migrate 7 backup CronJobs to Proxmox host NFS (192.168.1.127)
  (etcd, mysql, postgresql, nextcloud, redis, vaultwarden, plotting-book)
- Migrate headscale backup, ebook2audiobook, osm_routing to Proxmox NFS
- Migrate servarr (lidarr, readarr, soulseek) NFS refs to Proxmox
- Remove 79 orphaned TrueNAS NFS module declarations from 49 stacks
- Delete stacks/platform/modules/ (27 dead module copies, 65MB)
- Update nfs-truenas StorageClass to point to Proxmox (192.168.1.127)
- Remove iscsi DNS record from config.tfvars
- Fix woodpecker persistence config and alertmanager PV

Only Immich (8 PVCs, ~1.4TB) remains on TrueNAS.

stacks/speedtest/main.tf

@@ -53,14 +53,6 @@ resource "random_id" "secret_key" {
   byte_length = 32 # 32 bytes × 2 hex chars = 64 hex characters
 }
 
-module "nfs_config" {
-  source     = "../../modules/kubernetes/nfs_volume"
-  name       = "speedtest-config"
-  namespace  = kubernetes_namespace.speedtest.metadata[0].name
-  nfs_server = var.nfs_server
-  nfs_path   = "/mnt/main/speedtest"
-}
-
 resource "kubernetes_persistent_volume_claim" "config_proxmox" {
   wait_until_bound = false
   metadata {