feat(ansible): idempotent role-based host config for both production VMs

common/firewall/docker-tls/platform/lab-host/monitoring-agent/backup roles,
orchestrated by site.yml with the ordering that matters (firewall/TLS land
before the services that depend on them). Ansible Vault for secrets, no new
tool introduced for this project's modest secret surface. Explicit
dev/staging/production environment separation, no secrets committed
(.gitignore covers vault plaintext, TLS keys, Terraform state, *.env).

Validated: ansible-playbook --syntax-check clean.

infra/environments/production/provisioner-config/README.md

@@ -0,0 +1,15 @@
+# Production Provisioner config overlay
+
+Deployed by the `platform` Ansible role to `/etc/rootnode/provisioner-config/` on
+rn-platform-01 (`PROVISIONER_CONFIG_DIR`), replacing the dev-only files shipped in
+`platform/provisioner/config/`.
+
+- `lab-hosts.yaml` — points at the real rn-lab-host-01 VM over TLS instead of the dev Unix
+  socket. TLS paths reference material generated by `infra/scripts/docker-tls/` and deployed by
+  the `docker-tls` Ansible role — **never checked into this repo** (see
+  `infra/docker/tls/.gitignore`).
+- `resource-policy.yaml` — deliberately still the Phase 1 dev defaults, unchanged, with a
+  loud comment explaining why. Per the explicit Phase 4 instruction: do not hard-code final
+  per-Lab CPU/RAM numbers before the real host is benchmarked (`docs/CAPACITY_PLANNING.md`).
+  Whoever runs the first production load test (`infra/scripts/loadtest/`) updates this file
+  with real measured numbers, not this deployment.