docs(plan): scrub stale pack subdomain + packwiz from live-arch docs

The pack./packwiz service was removed operationally long ago, but several
plan docs still presented pack. as a live caddy vhost / DNS subdomain and
render-pack.sh as a current tool. Remove those references from the
current-architecture docs (overview, caddy, tooling, uptime-kuma,
letsencrypt, mc-backup); leave the migration log (04-mods.md), superseded
banner (04-packwiz.md), commit history (12-build-order.md), and planned
landing rework (18) intact as deliberate history.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plan/10-uptime-kuma.md

@@ -39,7 +39,7 @@ monitor stays green. Run both to tell *server down* apart from *path broken*.
 > Internal `minecraft` resolves because uptime-kuma is on `mcnet` (the container
 > name is the hostname). It is **not** routed through caddy — caddy only fronts
 > HTTP vhosts, and MC is raw TCP. Do not point the monitor at `caddy` or any
-> `status.`/`pack.` alias.
+> `status.` alias.
 
 ## Notes
 
@@ -50,6 +50,6 @@ monitor stays green. Run both to tell *server down* apart from *path broken*.
 - Put both MC monitors on the public **status page**
   (Settings → Status Pages) so guests can self-check before pinging you.
 - Optional companion HTTP monitors for the web stack:
-  `https://auth.${BASE_DOMAIN}`, `https://pack.${BASE_DOMAIN}/pack.toml`,
-  `https://${BASE_DOMAIN}` — a red `pack.toml` here explains client mod-mismatch
-  join failures.
+  `https://auth.${BASE_DOMAIN}`, `https://distribution.${BASE_DOMAIN}`,
+  `https://${BASE_DOMAIN}` — a red `distribution.` here explains client
+  mod-mismatch join failures.