[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/n8n/module/main.tf

@@ -0,0 +1,140 @@
+variable "tls_secret_name" {}
+variable "tier" { type = string }
+variable "postgresql_password" {}
+
+module "tls_secret" {
+  source          = "../../../modules/kubernetes/setup_tls_secret"
+  namespace       = kubernetes_namespace.n8n.metadata[0].name
+  tls_secret_name = var.tls_secret_name
+}
+
+resource "kubernetes_namespace" "n8n" {
+  metadata {
+    name = "n8n"
+    labels = {
+      tier = var.tier
+    }
+  }
+}
+
+resource "kubernetes_deployment" "n8n" {
+  metadata {
+    name      = "n8n"
+    namespace = kubernetes_namespace.n8n.metadata[0].name
+    labels = {
+      app  = "n8n"
+      tier = var.tier
+    }
+  }
+  spec {
+    replicas = 1
+    selector {
+      match_labels = {
+        app = "n8n"
+      }
+    }
+    template {
+      metadata {
+        labels = {
+          app = "n8n"
+        }
+      }
+      spec {
+        container {
+          name  = "n8n"
+          image = "docker.n8n.io/n8nio/n8n"
+          env {
+            name  = "DB_TYPE"
+            value = "postgresdb"
+          }
+          env {
+            name  = "DB_POSTGRESDB_DATABASE"
+            value = "n8n"
+          }
+          env {
+            name  = "DB_POSTGRESDB_HOST"
+            value = "postgresql.dbaas"
+          }
+          env {
+            name  = "DB_POSTGRESDB_PORT"
+            value = "5432"
+          }
+          env {
+            name  = "DB_POSTGRESDB_USER"
+            value = "n8n"
+          }
+          env {
+            name  = "DB_POSTGRESDB_PASSWORD"
+            value = var.postgresql_password
+          }
+          env {
+            name  = "GENERIC_TIMEZONE"
+            value = "Europe/Sofia"
+          }
+          env {
+            name  = "TZ"
+            value = "Europe/Sofia"
+          }
+          env {
+            name  = "DOMAIN_NAME"
+            value = "viktorbarzin.me"
+          }
+          env {
+            name  = "DOMAIN_NAME"
+            value = "n8n"
+          }
+          env {
+            name  = "N8N_EDITOR_BASE_URL"
+            value = "https://n8n.viktorbarzin.me"
+          }
+          env {
+            name  = "WEBHOOK_URL"
+            value = "https://n8n.viktorbarzin.me"
+          }
+          volume_mount {
+            name       = "data"
+            mount_path = "/home/node/.n8n"
+          }
+          port {
+            name           = "http"
+            container_port = 5678
+            protocol       = "TCP"
+          }
+        }
+        volume {
+          name = "data"
+          nfs {
+            path   = "/mnt/main/n8n"
+            server = "10.0.10.15"
+          }
+        }
+      }
+    }
+  }
+}
+
+resource "kubernetes_service" "n8n" {
+  metadata {
+    name      = "n8n"
+    namespace = kubernetes_namespace.n8n.metadata[0].name
+    labels = {
+      "app" = "n8n"
+    }
+  }
+
+  spec {
+    selector = {
+      app = "n8n"
+    }
+    port {
+      port        = "80"
+      target_port = "5678"
+    }
+  }
+}
+module "ingress" {
+  source          = "../../../modules/kubernetes/ingress_factory"
+  namespace       = kubernetes_namespace.n8n.metadata[0].name
+  name            = "n8n"
+  tls_secret_name = var.tls_secret_name
+}