Oikos Week 1: kernel policy, ontology, service contract, topology gen

Adds the Oikos agent-OS kernel: oikos/policy.yaml (risk classes +
approval rules for every homelab/MCP command), oikos/ontology.yaml
(8-domain systems model, typed relationships, node lifecycle), and
OIKOS.md (OODA loop operating brief, linked from AGENTS.md).

Extends inventory.yaml with a stable service contract (doc_page,
config_repo, risk_notes) on all 17 services, and a structured
archaeology: section for the 13 destroyed LXCs (was scattered
comments + a narrative table). Fixes stale drift found in the
process: authentik's backend pointed at a retired LXC (124); core
has run on the VPS since 2026-05-31.

Adds oikos/gen-topology.py, generating infrastructure/topology.md
(Mermaid compute/ingress + storage views) from inventory.yaml.
build_host_files.py now carries state/storage/depends_on into
generated hosts/*.yaml.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hosts/caddy.yaml

@@ -5,6 +5,7 @@ name: caddy
 kind: lxc
 os: linux
 role: reverse-proxy
+state: active
 host: hubris
 pve_id: 121
 lan_ip: 192.168.8.175
@@ -23,6 +24,10 @@ services_hosted:
   backend: caddy
   role: reverse-proxy
   note: terminates all *.hubris.network
+  doc_page: containers/121-caddy.md
+  config_repo: dtoro/caddy-conf
+  risk_notes: "wide blast radius \u2014 every *.hubris.network route rides on it (see oikos/policy.yaml\
+    \ service_overrides)"
 notes:
 - Terminates all *.hubris.network
 - /etc/caddy is a git checkout of dtoro/caddy-conf