docs: add host-disk-cleanup runbook + hk2 disk facts; record source -> Plane vps (VPS-81)

hosts/hk2.chans.xyz.md

@@ -185,6 +185,23 @@ dig @202.91.35.141 SOA wsvc.info +short
 
 On-server docs: `/opt/pdns/README.md`, `CHANGELOG.md`.
 
+## Disk / logging (VPS-81, 2026-09-02)
+
+Root disk cleanup performed (runbook: [host-disk-cleanup](../runbooks/host-disk-cleanup.md)):
+
+- Root `/` (20G vda1): 76% used → **38% used** (15G → 7.1G; free 4.7G → 12G).
+- **AGH log flood root cause fixed**: `/opt/adguard/conf/AdGuardHome.yaml`
+  `log.verbose: true → false` (backup `AdGuardHome.yaml.bak-20260902-vps81`).
+  Verbose debug was streaming to stderr → container `json.log` (~120MB/day);
+  `log.file: ""` makes AGH's own rotation keys inert. Restart only (no recreate).
+- Journald capped: `/etc/systemd/journald.conf.d/00-vps81.conf`
+  `SystemMaxUse=200M`; journal vacuumed to ~96M.
+- Docker: engine **29.7.2**; 14 unused images removed (kept `pdns-auth-50:5.0.5`
+  rollback pin); 12 orphan anonymous volumes + build cache pruned. In-use
+  volumes intact (`pdns_dbdata`, `b594d738…` PG data, `e855d078…` backup).
+- Follow-up: re-check AGH `json.log` growth **2026-09-09** (one-week checkpoint);
+  global docker log rotation only if still needed.
+
 ## Verified
 
 Last checked: **2026-08-01 21:40 CST** — operational; docs audit recorded.
@@ -194,3 +211,4 @@ Last checked: **2026-08-01 21:40 CST** — operational; docs audit recorded.
 - `only-notify=` + `also-notify=202.91.35.141`; MASTER `domains.master` cleared
 - https://pdns.wsvc.info → **302**; https://pgweb.wsvc.info → **401**
 - Hardening backlog: API/DB credential rotation + TSIG rotate (see upstream doc)
+- 2026-09-02 (VPS-81): post-cleanup verified — 10 containers Up (adguardhome healthy), DNS SOA/NS + web endpoints OK; see Disk/logging section above.