Fix Caddy ingress ACME email and RBAC issues

- Add acme_email_key constant for spec.yml parsing
- Add get_acme_email() method to Spec class
- Modify install_ingress_for_kind() to patch ConfigMap with email
- Pass acme-email from spec to ingress installation
- Add 'delete' verb to leases RBAC for certificate lock cleanup

The acme-email field in spec.yml was previously ignored, causing
Let's Encrypt to fail with "unable to parse email address".
The missing delete permission on leases caused lock cleanup failures.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

stack_orchestrator/constants.py

@@ -44,3 +44,4 @@ unlimited_memlock_key = "unlimited-memlock"
 runtime_class_key = "runtime-class"
 high_memlock_runtime = "high-memlock"
 high_memlock_spec_filename = "high-memlock-spec.json"
+acme_email_key = "acme-email"