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>

runbooks/lifecycle-deprecate-node.md

@@ -0,0 +1,35 @@
+---
+name: lifecycle-deprecate-node
+risk_class: config_mutation
+inputs: [node_name, replacement_node_or_reason]
+verification: "homelab node <name> relations — 'affected by' must be empty before completing"
+docs_update_checklist: [doc_page_deprecation_note]
+transition: "active -> deprecated"
+---
+
+# Lifecycle: deprecate a node
+
+Per [oikos/ontology.yaml](../oikos/ontology.yaml): a node keeps running
+but takes no new dependents. **Completion condition: zero remaining
+inbound `depends-on`/`routes-to` edges** — this is a hard gate, not a
+suggestion; `oikos/policy.yaml` `lifecycle_overrides.deprecated.refuse`
+lists `new-inbound-edges` as refused going forward.
+
+1. Set `state: deprecated` on the node.
+2. `homelab node <name> relations` — read `affected_by`. Every entry
+   there is something still relying on this node.
+3. Migrate or retire each dependent one at a time (point its `backend`/
+   `config_repo`/ingress route elsewhere, or deprecate it too if it's
+   being retired alongside).
+4. Re-run `homelab node <name> relations` after each dependent is moved.
+   The transition to `destroyed` is only safe once `affected_by` is
+   empty — check this every time, don't assume from memory.
+5. Note the deprecation on the doc page: reason, replacement (if any),
+   date.
+
+If step 2 shows dependents you didn't expect, stop and investigate
+before proceeding — that's exactly the kind of drift the Week-3 detector
+will catch automatically, but until then this manual check is the gate.
+
+Next (once `affected_by` is empty):
+[lifecycle-destroy-node.md](lifecycle-destroy-node.md).