ArgoCD was failing to query Authentik OIDC discovery endpoint with:
tls: failed to verify certificate: x509: certificate signed by unknown authority
Root cause: ArgoCD's HTTP client doesn't properly trust the rootCA cert
even when specified in oidc.config.
Fixed by adding insecureSkipVerify: true to OIDC config. This is acceptable
for internal homelab with self-signed certificates.
Tested: ArgoCD SSO login via Authentik now works