arch-migration P2: Technitium dns LXC (107); retire LXC 124

- containers/107-dns.md: new Technitium DNS server page
- dns.md: dnsmasq -> Technitium changelog; flags 3 overlapping DNS sources + router DHCP action
- 124-authentik: marked RETIRED (shut down)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

containers/107-dns.md

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+# 107 — `dns`
+
+Homelab DNS server (Technitium). Replaces the dnsmasq that lived on [124 — authentik](124-authentik.md); single-purpose, one job.
+
+## At a glance
+- **Hostname:** `dns`
+- **IP:** `192.168.8.2` (static — stable, decoupled from any app)
+- **Privilege:** privileged (Docker-in-LXC, `features: nesting=1`)
+- **Resources:** 1 core / 1 GiB / 8 GiB rootfs
+- **Created:** 2026-06-01, Debian 13. Its own resolver is `1.1.1.1` (no circular dependency on the DNS it serves).
+
+## Role
+Authoritative split-horizon DNS for `hubris.network` on the LAN/mesh, plus recursive forwarding (`1.1.1.1`, `8.8.8.8`) for everything else. Technitium runs in Docker (`technitium/dns-server:latest`, `network_mode: host`), web console on `:5380`.
+
+## The `hubris.network` zone
+- Specific A overrides: app names → `192.168.8.175` (Caddy), `nfs-export → 192.168.8.200`, `auth/sso/...` as needed.
+- `auth.hubris.network → 82.165.190.79` (VPS Authentik), `sso.hubris.network → 192.168.8.175` (LAN forward-auth outpost).
+- **Wildcard** `*.hubris.network → 82.165.190.79` — mirrors the public IONOS wildcard so undefined names (e.g. `netbird`) resolve to the VPS, matching public behaviour.
+- **MX / SPF-TXT / CAA replicated from public** so an authoritative zone doesn't shadow `hubris.network` email/cert records.
+
+## Config / access
+- `/opt/technitium/docker-compose.yml`; admin password in `/opt/technitium/admin_password.txt` (mode 600 — sops-encrypt in Phase 5).
+- Console: `http://192.168.8.2:5380` (user `admin`).
+- API: `http://192.168.8.2:5380/api/...` (token via `/api/user/login`). Zone was built via the API.
+
+## Who points here
+- **NetBird mesh peers:** nameserver group `home-lab-dns` (`hubris.network` → this server). *Note: the [NetBird managed DNS zone](124-authentik.md) still answers most app names directly, bypassing this — see the single-source-of-truth decision.*
+- **Plain LAN clients:** router DHCP should hand out `192.168.8.2` (update the router — the old `.180`/dnsmasq is gone).
+- **Secondary:** Mac Mini (planned, Phase 3) via AXFR zone transfer.
+
+## Related
+- [124 — authentik](124-authentik.md) — retired host of the old dnsmasq
+- [DNS split-horizon](../infrastructure/dns.md)
+- [Mesh](../infrastructure/mesh.md)
+
+## Changelog
+
+### 2026-06-01 — created; replaced dnsmasq on 124
+Stood up Technitium at `192.168.8.2`, imported the split-horizon zone (specific A + wildcard + MX/SPF/CAA), made it the primary nameserver in the NetBird `home-lab-dns` group. Verified all names resolve with dnsmasq/124 stopped; [LXC 124 retired](124-authentik.md).