Establish clean homelab infrastructure baseline

Reorganize the brownfield repository, remove retired and generated artifacts, harden ignore rules, and record the GitOps/IaC redesign.

apps/smtp-relay/terraform/versions.tf

@@ -0,0 +1,14 @@
+terraform {
+  required_version = ">= 1.5"
+  required_providers {
+    azuread = {
+      source  = "hashicorp/azuread"
+      version = "~> 3.0"
+    }
+  }
+}
+
+# Authenticates via Azure CLI by default: run `az login` as an account that can
+# create app registrations AND grant admin consent (Global Admin / Privileged Role
+# Admin) before `terraform apply`.
+provider "azuread" {}