GitLab cross-site replication Phase 1b: secret material sync

PushSecret (home) + ExternalSecret (VPS) pairs for the four
chart-generated secrets whose values must match before Phase 1c's
Postgres replication goes live: gitlab-rails-secret (secret_key_base/
db_key_base/otp_key_base/openid_connect_signing_key, all in one
secrets.yml key - confirmed live, not four separate keys as first
assumed), gitlab-gitlab-shell-secret, gitlab-gitaly-secret,
gitlab-praefect-secret (the latter two also needed for Phase 2's
cross-site gRPC auth). Same pattern as
infrastructure/authentik/manifests/ha-postgres-app-pushsecret.yaml.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/gitlab/manifests/ha-gitlab-secrets-pushsecret.yaml

@@ -0,0 +1,99 @@
+# GitLab cross-site replication Phase 1b (see
+# /home/scooby/.claude/plans/jiggly-snacking-iverson.md) - pushes home's
+# chart-generated secrets into Vault so the VPS's ESO can pull them back
+# down BEFORE the VPS's Postgres becomes a real replica of home's.
+#
+# Why this matters: the GitLab chart generates these per-release, at
+# random, on first install. Home's and the VPS's values are currently
+# different. Once the VPS's Postgres is byte-for-byte replicating home's
+# rows, the VPS Rails app will be reading home's encrypted-at-rest data
+# (2FA secrets, CI/CD variables, integration tokens, PAT digests,
+# application_settings encrypted columns) with the WRONG key unless these
+# match - Rails raises OpenSSL::Cipher::CipherError on boot otherwise.
+#
+# gitlab-gitaly-secret/gitlab-praefect-secret are also needed for
+# Phase 2's cross-site gRPC auth (the VPS's Gitaly/Praefect need the same
+# tokens home's do, to be trusted as nodes of the same virtual storage).
+#
+# Same pattern as infrastructure/authentik/manifests/ha-postgres-app-pushsecret.yaml.
+# Each of these secrets happens to have exactly one key (confirmed live),
+# so one PushSecret + one ExternalSecret per secret, no enumeration needed.
+apiVersion: external-secrets.io/v1alpha1
+kind: PushSecret
+metadata:
+  name: gitlab-rails-secret-to-vps
+  namespace: gitlab
+spec:
+  refreshInterval: 5m
+  secretStoreRefs:
+    - name: vault-backend
+      kind: ClusterSecretStore
+  selector:
+    secret:
+      name: gitlab-rails-secret
+  data:
+    - match:
+        secretKey: secrets.yml
+        remoteRef:
+          remoteKey: vps/gitlab-rails-secret
+          property: secrets.yml
+---
+apiVersion: external-secrets.io/v1alpha1
+kind: PushSecret
+metadata:
+  name: gitlab-shell-secret-to-vps
+  namespace: gitlab
+spec:
+  refreshInterval: 5m
+  secretStoreRefs:
+    - name: vault-backend
+      kind: ClusterSecretStore
+  selector:
+    secret:
+      name: gitlab-gitlab-shell-secret
+  data:
+    - match:
+        secretKey: secret
+        remoteRef:
+          remoteKey: vps/gitlab-gitlab-shell-secret
+          property: secret
+---
+apiVersion: external-secrets.io/v1alpha1
+kind: PushSecret
+metadata:
+  name: gitlab-gitaly-secret-to-vps
+  namespace: gitlab
+spec:
+  refreshInterval: 5m
+  secretStoreRefs:
+    - name: vault-backend
+      kind: ClusterSecretStore
+  selector:
+    secret:
+      name: gitlab-gitaly-secret
+  data:
+    - match:
+        secretKey: token
+        remoteRef:
+          remoteKey: vps/gitlab-gitaly-secret
+          property: token
+---
+apiVersion: external-secrets.io/v1alpha1
+kind: PushSecret
+metadata:
+  name: gitlab-praefect-secret-to-vps
+  namespace: gitlab
+spec:
+  refreshInterval: 5m
+  secretStoreRefs:
+    - name: vault-backend
+      kind: ClusterSecretStore
+  selector:
+    secret:
+      name: gitlab-praefect-secret
+  data:
+    - match:
+        secretKey: token
+        remoteRef:
+          remoteKey: vps/gitlab-praefect-secret
+          property: token