Add a stateful Proxmox API console and broad handler coverage beyond the

initial QEMU slice, backed by imported contracts for majors 6–9.
- Implement durable handlers for access/auth, cluster, LXC, storage, HA,
  firewall, Ceph, SDN, ACME, notifications, pools, mapping, and node ops
- Serve an interactive Web UI with catalog browsing, demo seed controls,
  and OpenAPI/help surfaces
- Bundle PVE 6.4-15, 7.4-16, and 8.4.5 contract revisions alongside 9.2.3
- Support in-memory runtime contract Apply (POST /ui/api/contract/apply)
  so /version and /api2 routes follow the selected major until restart
- Expand seed profiles (including demo-cluster), migrations 007–008, TLS
  gateway config, Compose/Makefile tooling, and compatibility evidence
- Tighten .gitignore for macOS, hidden directories (.*/), and local secrets

docs/domains/cluster-extras.md

@@ -0,0 +1,11 @@
+# Cluster extras
+
+Additional cluster-scoped domains with durable handlers:
+
+- **Notifications** — endpoints and targets configuration state
+- **ACME** — account/plugin/certificate simulation (no real CA enrollment)
+- **Mapping** — PCI / USB / resource mappings
+- **Metrics servers** — PVE metrics-server configuration/export simulation
+- **Custom CPU models** and bulk guest actions as declared
+
+Browse the Web UI catalog for the exact paths on your active major.