forgejo pulls: route *.viktorbarzin.me to Technitium, drop /etc/hosts pins [ci skip]

Supersedes this morning's per-node /etc/hosts pin (no hardcoded service
IPs on nodes, per Viktor). Technitium's split-horizon zone already
resolves forgejo.viktorbarzin.me -> CNAME apex -> live Traefik LB IP
(ingress-dns-sync auto-CNAMEs every ingress host; apex drift probe
alerts) -- the nodes just never queried it. Rolled the devvm's
systemd-resolved routing-domain pattern (~viktorbarzin.me ->
10.0.20.201) to all 7 nodes, removed the pins, verified getent +
crictl pull via pure DNS.

Also demoted node5/6's cloud-init global-dns.conf (DNS=8.8.8.8 1.1.1.1)
to FallbackDNS-only: public servers in the global set race the routing
domain. Its justification ("Technitium NXDOMAINs forgejo") was obsolete
-- exactly the stale comment that pointed new nodes at the hairpin.

hosts.toml mirror kept but documented as vestigial (Traefik 404s
bare-IP requests; registry auth realm is an absolute URL).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/architecture/dns.md

@@ -269,10 +269,11 @@ Technitium's **Split Horizon AddressTranslation** app post-processes DNS respons
 
 - **Affected**: Non-proxied domains (ha-sofia, immich, headscale, calibre, vaultwarden, etc.) for 192.168.1.x clients
 - **Not affected**: Cloudflare-proxied domains (resolve to Cloudflare edge IPs, no translation needed)
-- **Not affected**: 10.0.x.x and K8s clients — these resolve non-proxied domains to the public IP and rely on pfSense NAT reflection, which is **intermittently broken** (observed i/o timeouts to `176.12.22.76:443` from k8s nodes and the devvm, 2026-06-04 → 2026-06-10). Hairpin-sensitive paths on this network get explicit per-leg fixes instead:
-  - **kubelet image pulls of `forgejo.viktorbarzin.me`**: `/etc/hosts` pin `10.0.20.203 forgejo.viktorbarzin.me` on every k8s node (marker `forgejo-internal-pin`; deployed via `modules/create-template-vm/k8s-node-containerd-setup.sh` for new nodes, `scripts/setup-forgejo-containerd-mirror.sh` rollout for existing ones). The containerd hosts.toml mirror alone is insufficient — Traefik 404s its bare-IP requests (no Host/SNI match) and the registry's Bearer auth realm is an absolute public URL fetched outside the mirror. Root cause of the 2026-06-10 tuya-bridge outage (`docs/post-mortems/2026-06-10-tuya-bridge-forgejo-pull-hairpin.md`).
-  - **in-cluster pods → forgejo**: CoreDNS `rewrite name exact forgejo.viktorbarzin.me traefik.traefik.svc.cluster.local` (2026-06-04, beads code-yh33).
-  - **devvm git → forgejo**: still exposed to the hairpin (manual `/etc/hosts` pin workaround when it flares).
+- **Not affected**: 10.0.x.x and K8s clients — these resolve non-proxied domains to the public IP and rely on pfSense NAT reflection, which is **intermittently broken** (observed i/o timeouts to `176.12.22.76:443` from k8s nodes and the devvm, 2026-06-04 → 2026-06-10). Hairpin-sensitive paths on this network route `*.viktorbarzin.me` to Technitium instead, via a systemd-resolved **routing domain** (`/etc/systemd/resolved.conf.d/viktorbarzin.conf`: `DNS=10.0.20.201`, `Domains=~viktorbarzin.me`). Technitium's split-horizon zone answers with the zone apex A record, which auto-tracks the live Traefik LB IP (`technitium-ingress-dns-sync` CNAMEs every ingress host hourly; `viktorbarzin-apex-probe` is the drift canary) — no hardcoded service IPs on clients:
+  - **k8s nodes (kubelet image pulls of `forgejo.viktorbarzin.me`)**: routing-domain drop-in on all 7 nodes (2026-06-10, replacing a same-day `/etc/hosts` pin; deployed via `modules/create-template-vm/cloud_init.yaml` for new nodes, `scripts/setup-forgejo-containerd-mirror.sh` rollout for existing ones). The containerd hosts.toml mirror alone is insufficient — Traefik 404s its bare-IP requests (no Host/SNI match) and the registry's Bearer auth realm is an absolute public URL fetched outside the mirror. Caution: public servers must NOT sit in the nodes' global resolved `DNS=` set — they merge with and race the routing domain (the old node5/6 `global-dns.conf` did exactly this; now `FallbackDNS=` only). Root cause analysis: `docs/post-mortems/2026-06-10-tuya-bridge-forgejo-pull-hairpin.md`.
+  - **devvm**: same `viktorbarzin.conf` drop-in (predates the node rollout; provisioned by `setup-devvm.sh`).
+  - **in-cluster pods → forgejo**: CoreDNS `rewrite name exact forgejo.viktorbarzin.me traefik.traefik.svc.cluster.local` (2026-06-04, beads code-yh33) — pods bypass node resolved entirely.
+  - **Trade-off**: `*.viktorbarzin.me` resolution from nodes/devvm now depends on in-cluster Technitium (3 replicas). During a full cluster outage these names SERVFAIL — acceptable, the services behind them are down anyway; bootstrap images pull via the IP-addressed `10.0.20.10` mirrors, so cold-start self-unwinds.
 
 Config is synced to all 3 Technitium instances by CronJob `technitium-split-horizon-sync` (every 6h).