monitoring01: remove host and migrate services to monitoring02

Remove monitoring01 host configuration and unused service modules
(prometheus, grafana, loki, tempo, pyroscope). Migrate blackbox,
exportarr, and pve exporters to monitoring02 with scrape configs
moved to VictoriaMetrics. Update alert rules, terraform vault
policies/secrets, http-proxy entries, and documentation to reflect
the monitoring02 migration.

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

README.md

@@ -10,7 +10,7 @@ NixOS Flake-based configuration repository for a homelab infrastructure. All hos
 | `ca` | Internal Certificate Authority |
 | `ha1` | Home Assistant + Zigbee2MQTT + Mosquitto |
 | `http-proxy` | Reverse proxy |
-| `monitoring01` | Prometheus, Grafana, Loki, Tempo, Pyroscope |
+| `monitoring02` | VictoriaMetrics, Grafana, Loki, Alertmanager |
 | `jelly01` | Jellyfin media server |
 | `nix-cache02` | Nix binary cache + NATS-based build service |
 | `nats1` | NATS messaging |
@@ -121,4 +121,4 @@ No manual intervention is required after `tofu apply`.
 - Infrastructure subnet: `10.69.13.0/24`
 - DNS: ns1/ns2 authoritative with primary-secondary AXFR
 - Internal CA for TLS certificates (migrating from step-ca to OpenBao PKI)
-- Centralized monitoring at monitoring01
+- Centralized monitoring at monitoring02