feat(igotify): wire the assist bridge with a Gotify client token

The bridge runs server-side, so it cannot run a browser flow and ZITADEL has no
part in it. Give it a Gotify client token instead: GOTIFY_URLS points at the
public host, GOTIFY_CLIENT_TOKENS comes from a SOPS secret.

The token belongs to user `rock`, is named igotify-assist, and has
expiresAfterInactivitySeconds 0 so it never idles out. Delete the client row in
Gotify to revoke it.

Verified with the token: GET /client returns 200 and GET /message returns the
latest message.

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
+    - igotify-client-token.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