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>

plans/2026-07-05-oikos-prometheus-lxc.md

@@ -42,7 +42,7 @@ is actually unused end-to-end.
 
 ## Provisioning steps (once pve_id is assigned)
 
-Follow [runbooks/lifecycle-provision-node.md](../runbooks/lifecycle-provision-node.md):
+Follow [lifecycle-provision-node](../.agents/skills/lifecycle-provision-node/SKILL.md):
 
 1. `pct create <new-id> ...` on hubris — confirm the assigned ID doesn't
    collide with 131 or anything else live.
@@ -53,7 +53,7 @@ Follow [runbooks/lifecycle-provision-node.md](../runbooks/lifecycle-provision-no
 4. Point node_exporter at hubris + strong (either install locally on each,
    or scrape via SSH-tunneled metrics — install locally is simpler and is
    the standard approach).
-5. Follow [runbooks/lifecycle-activate-node.md](../runbooks/lifecycle-activate-node.md)
+5. Follow [lifecycle-activate-node](../.agents/skills/lifecycle-activate-node/SKILL.md)
    to flip to `active`, complete the doc page, regenerate
    `hosts/*.yaml` + `infrastructure/topology.md`.
 6. Extend `oikos/scheduler.py`'s disk/temp probes to query Prometheus