monitoring: document Loki/Alloy/pve-exporter, dashboards and alerts

CT 109 ops stack now includes Loki (log agg), Grafana Alloy (log agent on
all 12 hosts), prometheus-pve-exporter. 5 Grafana dashboards imported;
3 alert rules wired to Gotify.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/homelab-architecture.md

@@ -24,7 +24,7 @@ across ~23 compose stacks. Principle: **self-host everything**, OIDC SSO,
   - `108` lxc **zoraxy** — reverse proxy (2c/2G) → `.4`
   - `110` lxc **id** — Pocket-ID OIDC IdP (1c/1G/4G) → `.5`; migrated off 104 on 2026-05-20
   - `111` lxc **dev** — Coder + Gitea (12c/32G/60G) → `.42`; new 2026-05-20
-  - `109` lxc **ops** `192.168.1.8` — Prometheus + Grafana + node-exporter (2026-05-23); future: Loki, Arcane, Dozzle, Homarr, Tinyauth
+  - `109` lxc **ops** `192.168.1.8` — Prometheus + Grafana + Loki + Alloy + pve-exporter (2026-05-23); future: Arcane, Dozzle, Homarr, Tinyauth
   - `113` lxc **db** — postgres 17 + pgAdmin + WAL-G → Garage S3 + Arcane edge agent → `.6`; provisioned 2026-05-21
   - Storages: `local` (dir), `local-zfs` (zfspool, ~1.9T), `unas` (nfs, ~20T).
 - **Ubiquiti UniFi** — UDM "Home" (UDMA6A8, UCG Fiber) gateway + 4× U7-series
@@ -394,7 +394,7 @@ flowchart TB
     docker104["<b>CT 104 · docker</b><br/>(.40) · 16c/48G/200G<br/>~65 containers · Intel Arc passthrough"]
     nc["CT 105 · nextcloud<br/>(.41)<br/>Nextcloud AIO (NFS)"]
     zoraxy["CT 108 · zoraxy<br/>(.4)<br/>reverse proxy + ACME"]
-    obs["CT 109 · ops<br/>(.8)<br/>Prometheus · Grafana"]
+    obs["CT 109 · ops<br/>(.8)<br/>Prometheus · Grafana · Loki · Alloy · pve-exporter"]
     id["CT 110 · id<br/>(.5)<br/>Pocket-ID (moved here 2026-05-20)"]
     dev["CT 111 · dev<br/>(.42) · 12c/32G/60G<br/>Coder + Gitea + workspaces · Intel Arc"]
     db["CT 113 · db<br/>(.6) · provisioned 2026-05-21<br/>shared Postgres + pgAdmin"]