docs: reshape runbooks into .agents/skills/<name>/SKILL.md (phase 4)

Problem: runbooks are agent-executable procedures but lived at the repo root,
separate from the other agent instruction now under .agents/.

Change:
- Move runbooks/<name>.md -> .agents/skills/<name>/SKILL.md (folder per skill,
  matching the wiki-hq skills layout). Frontmatter (name, risk_class, inputs,
  verification, docs_update_checklist, transition) preserved.
- Rewrite links (inbound from plans; between-skill siblings) via the move map.
- Update prose references in AGENTS.md, HERMES.md, .agents/OIKOS.md, and the
  operations schema; fix a pre-existing stale link to operations/commands.md.

No code consumed runbooks/ by path, so nothing else changes.

Verification: all SKILL.md frontmatter parses with valid risk_class; every
lifecycle transition resolves to an oikos/ontology.yaml state; broken-link
count 127 -> 126 (fixed one, introduced none).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.agents/skills/lifecycle-migrate-node/SKILL.md

@@ -0,0 +1,39 @@
+---
+name: lifecycle-migrate-node
+risk_class: config_mutation
+inputs: [node_name, source_host, target_host]
+verification: "homelab node <name> relations (re-check blast radius); homelab service <svc> health for every hosted service"
+docs_update_checklist: [doc_page_migration_note, inventory_host_and_lan_ip]
+transition: "active -> migrating -> active"
+---
+
+# Lifecycle: migrate a node
+
+Modeled on the strong Phase 1+2 migration
+([plans/2026-06-03_110000-library-ssd-migration-to-ludo-mini.md](../../../plans/2026-06-03_110000-library-ssd-migration-to-ludo-mini.md)).
+Requires (ontology): preflight + backup-verified before migrating;
+post-verify + Caddy backends checked + mounts checked + docs updated
+before returning to `active`.
+
+1. `homelab change preflight <every service the node hosts>` — capture
+   current health as a baseline.
+2. Verify backups are current for anything with data at rest on the
+   node (see `backs-up-to` edges once populated).
+3. Set `state: migrating` in `inventory.yaml`.
+4. Perform the migration (pct/qm move, or create-on-target +
+   data-copy + destroy-source, per the specific case).
+5. Update `inventory.yaml`: new `host:`, `lan_ip`, `mesh` addresses for
+   the node; update every `services:` entry whose `backend` pointed at
+   it if the backend name itself changes (usually it doesn't — only the
+   `host:`/`lan_ip` on the guest entry moves).
+6. Post-verify: re-run the Week-1 drift check by hand — confirm Caddy's
+   backend IP for each affected service matches the new `lan_ip`
+   (automatic in Week 3's drift detector), confirm mounts still resolve.
+7. `homelab service <name> health` for every service the node hosts.
+8. Set `state: active`. Add a migration note to the node's doc page
+   (old host/IP → new, date, phase reference) — this repo's convention
+   for every past migration (see `containers/101-jellyfin.md`,
+   `containers/129-house.md`).
+
+Regenerate: `python3 mcp/build_host_files.py && python3
+oikos/gen-topology.py`.