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/client-enrollment/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: client-enrollment
+risk_class: config_mutation
+inputs: [hostname, kind, role]
+verification: "homelab doctor (on the new client)"
+docs_update_checklist: [hosts_narrative_page_if_lxc_or_vm]
+---
+
+# Client enrollment
+
+Goal: bring a new host (workstation, LXC, VM) into inventory and the
+secrets model, with mesh membership only where it's actually needed.
+This wraps the existing `homelab client add` flow — see
+[operations/agent-enrollment.md](../../../operations/agent-enrollment.md) for
+the full walkthrough; this runbook is the risk/lifecycle framing.
+
+1. On any enrolled client: `homelab client add <hostname>` — appends a
+   `hosts.<name>:` block to `inventory.yaml` (lifecycle `state: planned`
+   → `provisioning`, per [oikos/ontology.yaml](../../../oikos/ontology.yaml)),
+   commits + pushes.
+2. Netbird join is **optional, not a required step** — only needed for
+   hosts that must be reachable off-LAN (workstations that roam, e.g.
+   `republic-laptop`, `mac-mini`). A node reachable on the household LAN
+   (192.168.8.0/24 — most LXCs/VMs) doesn't need it: it's already
+   reachable directly, and off-LAN clients reach it too via hubris's
+   routed `192.168.8.0/24` Netbird network resource. Skip this step for
+   LAN-only nodes; do it (out-of-band, console or setup key) only for
+   hosts that need independent off-LAN reachability.
+3. On the new host: run `bootstrap.sh` (add `--with-hermes` to also
+   enroll the Hermes agent). This provisions `/etc/age/key.txt`, the
+   sync timer, and prints an age pubkey.
+4. Back on an enrolled client: `homelab client add <hostname>
+   --finalize-pubkey <age1...>` — sets `age_pubkey`, grants shared
+   secrets, re-keys SOPS, commits + pushes. This is the
+   `provisioning → active` transition.
+5. Verify: `homelab doctor` on the new client should show all checks
+   green (clone, sync timer, age key, CLI symlink, MCP reachable).
+
+Docs-update checklist: if the new host is an LXC/VM, add its narrative
+page under `containers/` or `vms/` and set `doc_page` in its inventory
+entry (host-level cards don't have a `doc_page` field yet — services do;
+narrative pages are still found via the generated `see_also` in
+`hosts/<name>.yaml`).