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/secret.example.yaml

@@ -0,0 +1,19 @@
+# Copy to secret.yaml (gitignored) and fill in — or let the Terraform in ./terraform/
+# emit these values (it creates the Entra app registration + client secret).
+#
+#   CLIENT_ID     = Application (client) ID of the Entra app registration
+#   CLIENT_SECRET = a client secret VALUE for that app (used by sasl-xoauth2 to refresh)
+#   TENANT_ID     = your Entra tenant (directory) ID
+#
+# NOTE: these three are NOT the whole story — the relay also needs a device-code
+# refresh token minted once into the PVC (see README "Bootstrap the token").
+apiVersion: v1
+kind: Secret
+metadata:
+  name: smtp-relay-secret
+  namespace: smtp-relay
+type: Opaque
+stringData:
+  CLIENT_ID: 'CHANGE-ME'
+  CLIENT_SECRET: 'CHANGE-ME'
+  TENANT_ID: 'CHANGE-ME'