feat(iam): wire ZITADEL SMTP through envVarsSecret

ZITADEL must send verification codes, and it only speaks SMTP. Route that at
the smtp-gotify relay so codes reach Gotify and the phone.

The settings go in as a ZITADEL_DEFAULTINSTANCE_SMTPCONFIGURATION_* envFrom
secret, not as configmapConfig. Editing configmapConfig makes ArgoCD stop
managing the rendered zitadel-config-yaml ConfigMap, which the Deployment still
mounts; that twice left the IdP one restart away from failing. Env vars override
the same keys and leave that ConfigMap alone.

Validated with helm template 10.4.0: envFrom appears on both ZITADEL containers
and zitadel-config-yaml still renders.

k8s/argocd/secrets/secret-generator.yaml

@@ -36,6 +36,7 @@ files:
     - etcd-defrag-creds.enc.yaml
     - zitadel-masterkey.enc.yaml
     - smtp-gotify-secrets.enc.yaml
+    - zitadel-smtp-secrets.enc.yaml
     # Login UI RSA keypair, adopted from the chart-generated Secret so ArgoCD
     # owns it. Without this, the chart re-generates the keypair on every render,
     # which changes checksum/secret-login-service-key and leaves both Zitadel

k8s/argocd/secrets/zitadel-smtp-secrets.enc.yaml

@@ -0,0 +1,25 @@
+apiVersion: v1
+kind: Secret
+metadata:
+    name: zitadel-smtp-env
+    namespace: iam
+stringData:
+    ZITADEL_DEFAULTINSTANCE_SMTPCONFIGURATION_SMTP_HOST: ENC[AES256_GCM,data:c1O6xqe9O7b6OzDCYSQJjqkCvc7cisM/dIgGu3aC6yZGIFuuvfE=,iv:aAVqKCgi8NspPAiIKsgK4yfy8CDqAO2Y/GVdUKpVoGc=,tag:2t1GkBBVyimKorM291cR6A==,type:str]
+    ZITADEL_DEFAULTINSTANCE_SMTPCONFIGURATION_TLS: ENC[AES256_GCM,data:Pni4WpI=,iv:g11iVRNTYs9VHjX7TATYkzgFR1UQ0QbpXlXxfkEwzQQ=,tag:VzJeOG58w7RqCMk7NZJNxw==,type:str]
+    ZITADEL_DEFAULTINSTANCE_SMTPCONFIGURATION_FROM: ENC[AES256_GCM,data:ldRZWrqh+geS9ooxaH4kXbkJinE=,iv:ZPOrJj5R5i5FOvRvObNE/Fw2oPKyH/lw7+pUSP1qE8o=,tag:fsICt7sB4De44VLy3v2nsQ==,type:str]
+    ZITADEL_DEFAULTINSTANCE_SMTPCONFIGURATION_FROMNAME: ENC[AES256_GCM,data:DpRonnBJpQ==,iv:+oucgXGstpvduMhZIZjmrvbbm8gixr2D2zET410fXRw=,tag:eTVFhvg+Xnr4m6o+iFWVAw==,type:str]
+sops:
+    age:
+        - enc: |
+            -----BEGIN AGE ENCRYPTED FILE-----
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSA1eVFtenRNQXBKNndNZXpO
+            TXJoWWF1V2xnNUV2dVpxeXZWelBNVFZnTlFRCmUzT1RNL1lXbmMvR25LdWtrTXBB
+            WWNZK3hLRCtDVWl0enhLZmVpVjBlclEKLS0tIGYyWTlMaXQzbG12aGxTQi9CcnRM
+            UjRUOGJmQkZiU0I4L1MzaG1seFNJdncKqI3pFbUKj16946H2p9AHSK2DSArvo5Ep
+            y8y/aYc+NNPBaJzy/cdo9aI2mT4tNuw0IsM4f0VXlfEIc3teR5hdNA==
+            -----END AGE ENCRYPTED FILE-----
+          recipient: age1e5fq3hwxy78psus2nfvmtmua36g0u3suk78ephw6246l974d2utsvn0hla
+    encrypted_regex: ^(data|stringData)$
+    lastmodified: "2026-10-27T06:45:46Z"
+    mac: ENC[AES256_GCM,data:ec9gwKHWtajOyPO5+4ZEAhCuLSlmbQWgcJXL+I/E32/AIoc8NX4Ec8AoeURbfCiknYgeTizAKA2BAipJkZQPev/6j3tuwLI5A34k1g1ax7gdc1gGvEZEpJ03u5PUgJRXfHi4mgSSdF1MrasogOUe2tYSwVwF+HnByBTvxj6HOzk=,iv:8EuCICwZghS4u8PQ0bJwTwTOo12zlVPGOp9+qqJ/Kt0=,tag:CkJGpzS7lGe3SOBtRId9Kg==,type:str]
+    version: 3.13.2

k8s/infra/iam/zitadel-values.yaml

@@ -145,6 +145,20 @@ setupJob:
 replicaCount: 2
 revisionHistoryLimit: 3
 
+# Notification delivery. ZITADEL sends verification codes and password resets
+# by SMTP only, and this cluster has no mail path, so every user sits at
+# verified_email = empty and cannot finish a first login.
+#
+# The settings go in through envVarsSecret rather than configmapConfig on
+# purpose: changing configmapConfig makes ArgoCD stop managing the rendered
+# `zitadel-config-yaml` ConfigMap, which the Deployment still mounts, so the
+# next pod restart fails. An envFrom secret overrides the same keys with no
+# effect on that ConfigMap.
+#
+# Target is the in-cluster smtp-gotify relay, which forwards to Gotify so the
+# codes arrive on the phone.
+envVarsSecret: zitadel-smtp-env
+
 # Best practice: a PDB guarantees at least one API pod stays available during
 # voluntary disruptions (node drain, rolling upgrade). Without it a drain can
 # take both replicas down at once. minAvailable 1 is correct for 2 replicas;