Oikos Week 2: Service Console v0, change ledger, node relations, runbooks

Adds the shared kernel modules (oikos/policy.py, oikos/relations.py,
oikos/ledger.py) that let every surface — CLI, MCP, context-card
generator — agree on risk classification and ontology graph walks
from one implementation.

homelab CLI: `service <name> explain|health|docs|log|actions|history`
(Service Console v0), `change preflight <service>`, `node <name>
relations`. Restart and client add/remove now append change-ledger
entries (ledger/*.jsonl, committed alongside the change they record).

mcp/server.py mirrors explain/preflight/get_relations/get_change_history
as MCP tools, card-first so agent orientation is one call instead of
several search_docs/get_page round-trips.

oikos/gen-topology.py now also emits a compact context card per host
and service (oikos/cards/*.md) — identity, blast radius, safe actions +
risk class, doc pointer, recent ledger history.

runbooks/*.md: service health check, config change + deploy, client
enrollment, incident investigation, and the five node lifecycle
transitions (provision/activate/migrate/deprecate/destroy), each with
machine-readable frontmatter (risk class, inputs, verification,
docs-update checklist). Wired into HERMES.md so agents load these
instead of rediscovering topology per-task.

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

oikos/cards/host-strong.md

@@ -0,0 +1,19 @@
+# strong (host:strong)
+
+- kind: proxmox-host
+- state: active
+- role: hypervisor
+- address: 192.168.178.181
+- doc: hosts/strong.md
+- secrets: enrolled (age key present)
+
+## Blast radius
+- impacts: host:arriman, host:elementsynapse, host:grimmory, host:house, host:jellyfin, host:romm, host:seanime
+- affected by: (none)
+- full blast radius: host:arriman, host:elementsynapse, host:grimmory, host:house, host:jellyfin, host:romm, host:seanime, service:arr_stack, service:jellyfin, service:matrix
+
+## Safe actions
+- see the services this host runs for action-level risk classes
+
+## Recent changes
+- (none yet)