system: enable homelab-deploy listener for all vault hosts

Add system/homelab-deploy.nix module that automatically enables the
listener on all hosts with vault.enable=true. Uses homelab.host.tier
and homelab.host.role for NATS subject subscriptions.

- Add homelab-deploy access to all host AppRole policies
- Remove manual listener config from vaulttest01 (now handled by system module)

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

system/default.nix

@@ -3,6 +3,7 @@
   imports = [
     ./acme.nix
     ./autoupgrade.nix
+    ./homelab-deploy.nix
     ./monitoring
     ./motd.nix
     ./packages.nix