refactor!: unify into one compose, drop airgap/mirror/dnsmasq/avahi/blessingskin

Collapse the override-file matrix into a single docker-compose.yml holding the
whole stack: drasl, minecraft, mc-backup, caddy, nmsr, uptime-kuma. Bring-up is
now just `docker compose up -d --build`.

Removed features (dead-ends for this deployment):
- airgap / full asset mirror (mirror-airgap.sh, mirror-mods.sh, 20-mirror.caddy,
  caddy local-CA export, /ca.crt)
- dnsmasq + avahi/mDNS + dns-records.sh + mdns-host-setup.sh + ENABLE_MDNS;
  DNS is now handled outside this repo (HOST_LAN_IP dropped)
- Blessing Skin auth variant (compose + 00-core-blessingskin.caddy + BS_* env)
- host-nginx-static variant (docker-compose.nginx.yml, nginx/ulicraft.conf.tmpl)
- build-stack.sh and its run modes (online/airgap/core)

Production ingress is the only path now: host nginx terminates TLS (LE certs)
in front of caddy on a localhost-only port; caddy routes every vhost by Host
header. Launcher downloads move mirror/launcher -> launcher/.

Docs: README, deploy skill, and plan/ rewritten to match; obsolete plan docs
(dnsmasq, blessing-skin, assets-mirror, full-airgap-mirror, dns-and-run-modes)
deleted.

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

tooling/fetch-launcher.sh

@@ -3,7 +3,7 @@
 # offline LAN hosting, then create stable-name symlinks for the landing page.
 #
 # Guests use FjordLauncherUnlocked (Prism/PolyMC fork with authlib-injector
-# built in). We mirror every release asset under mirror/launcher/<tag>/ and
+# built in). We mirror every release asset under launcher/<tag>/ and
 # maintain a `latest` symlink → <tag>. Caddy serves this at /launcher/latest/…
 #
 # The landing page (landing/src/data/site.ts) links to FIXED filenames so the
@@ -16,11 +16,11 @@
 # Cautious by design: halts on any error, and if a stable-name category matches
 # 0 or >1 candidate it prints the candidates and exits non-zero rather than
 # guessing. Idempotent — re-runs overwrite symlinks and re-download safely.
-# mirror/ is gitignored — only this script is tracked.
+# launcher/ is gitignored — only this script is tracked.
 set -euo pipefail
 
 REPO="hero-persson/FjordLauncherUnlocked"
-DEST_ROOT="$(dirname "$0")/../mirror/launcher"
+DEST_ROOT="$(dirname "$0")/../launcher"
 API="https://api.github.com/repos/${REPO}/releases/latest"
 
 command -v curl >/dev/null || { echo "curl required" >&2; exit 1; }