extract remaining 19 modules from platform, complete stack split [ci skip]

Phase 3: all 27 platform modules now run as independent stacks.
Platform reduced to empty shell (outputs only) for backward compat
with 72 app stacks that declare dependency "platform".
Fixed technitium cross-module dashboard reference by copying file.
Woodpecker pipeline applies all 27+1 stacks in parallel via loop.
All applied with zero destroys.

stacks/rbac/main.tf

@@ -0,0 +1,23 @@
+variable "tls_secret_name" { type = string }
+variable "ssh_private_key" {
+  type      = string
+  default   = ""
+  sensitive = true
+}
+
+data "vault_kv_secret_v2" "secrets" {
+  mount = "secret"
+  name  = "platform"
+}
+
+locals {
+  k8s_users = jsondecode(data.vault_kv_secret_v2.secrets.data["k8s_users"])
+}
+
+module "rbac" {
+  source          = "./modules/rbac"
+  tier            = local.tiers.cluster
+  tls_secret_name = var.tls_secret_name
+  k8s_users       = local.k8s_users
+  ssh_private_key = var.ssh_private_key
+}