[ci skip] Move Terraform modules into stack directories

Move all 88 service modules (66 individual + 22 platform) from
modules/kubernetes/<service>/ into their corresponding stack directories:

- Service stacks: stacks/<service>/module/
- Platform stack: stacks/platform/modules/<service>/

This collocates module source code with its Terragrunt definition.
Only shared utility modules remain in modules/kubernetes/:
ingress_factory, setup_tls_secret, dockerhub_secret, oauth-proxy.

All cross-references to shared modules updated to use correct
relative paths. Verified with terragrunt run --all -- plan:
0 adds, 0 destroys across all 68 stacks.

stacks/platform/modules/authentik/main.tf

@@ -0,0 +1,72 @@
+variable "tls_secret_name" {}
+variable "secret_key" {}
+variable "postgres_password" {}
+variable "tier" { type = string }
+
+
+module "tls_secret" {
+  source          = "../../../../modules/kubernetes/setup_tls_secret"
+  namespace       = kubernetes_namespace.authentik.metadata[0].name
+  tls_secret_name = var.tls_secret_name
+}
+
+resource "kubernetes_namespace" "authentik" {
+  metadata {
+    name = "authentik"
+    labels = {
+      tier                                = var.tier
+      "resource-governance/custom-quota" = "true"
+    }
+  }
+}
+
+resource "kubernetes_resource_quota" "authentik" {
+  metadata {
+    name      = "authentik-quota"
+    namespace = kubernetes_namespace.authentik.metadata[0].name
+  }
+  spec {
+    hard = {
+      "requests.cpu"    = "8"
+      "requests.memory" = "8Gi"
+      "limits.cpu"      = "24"
+      "limits.memory"   = "48Gi"
+      pods              = "30"
+    }
+  }
+}
+
+resource "helm_release" "authentik" {
+  namespace        = kubernetes_namespace.authentik.metadata[0].name
+  create_namespace = true
+  name             = "goauthentik"
+
+  repository = "https://charts.goauthentik.io/"
+  chart      = "authentik"
+  # version    = "2025.8.1"
+  version = "2025.10.3"
+  atomic  = true
+  timeout = 6000
+
+  values = [templatefile("${path.module}/values.yaml", { postgres_password = var.postgres_password, secret_key = var.secret_key })]
+}
+
+
+module "ingress" {
+  source          = "../../../../modules/kubernetes/ingress_factory"
+  namespace       = kubernetes_namespace.authentik.metadata[0].name
+  name            = "authentik"
+  service_name    = "goauthentik-server"
+  tls_secret_name = var.tls_secret_name
+}
+
+module "ingress-outpost" {
+  source          = "../../../../modules/kubernetes/ingress_factory"
+  namespace       = kubernetes_namespace.authentik.metadata[0].name
+  name            = "authentik-outpost"
+  host            = "authentik"
+  service_name    = "ak-outpost-authentik-embedded-outpost"
+  port            = 9000
+  ingress_path    = ["/outpost.goauthentik.io"]
+  tls_secret_name = var.tls_secret_name
+}