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/service-health-check.md

@@ -0,0 +1,30 @@
+---
+name: service-health-check
+risk_class: read_only
+inputs: [service_name]
+verification: "homelab service <name> health"
+docs_update_checklist: []
+---
+
+# Service health check
+
+Goal: determine whether a service is actually healthy, without ad-hoc SSH.
+
+1. `homelab service <name> explain` — read the context card: backend,
+   blast radius, doc pointer, risk notes.
+2. `homelab service <name> health` — live health probe (HTTP code against
+   the service's `url`/`endpoint`). Once the Week-3 scheduler ships, this
+   reads a cached snapshot by default; pass `--live` to force a fresh probe.
+3. If unhealthy, `homelab service <name> log` (or MCP `tail_log`) for the
+   last 200 lines.
+4. Cross-check blast radius: `homelab node <name> relations` — is this
+   entity's own backend host healthy? A downstream failure (e.g. `strong`
+   down) will show up here before the service's own logs explain anything.
+5. If the fix is a restart: classify first (`oikos/policy.yaml` —
+   `service-restart` is `reversible_low` unless the service has a
+   `service_overrides` entry, e.g. `caddy`/`dns` are `config_mutation`).
+   Unattended agents may act on `reversible_low` without approval.
+
+Docs-update checklist: none for a pure health check. If the investigation
+reveals stale `risk_notes` or a wrong `doc_page`, fix `inventory.yaml` in
+the same session.