Serve modpack.zip via Caddy static file, not Gitea (50MB cap)

modpack-final.zip is 78MB, well over Gitea's upload limit. Served
directly from Caddy's existing static/ mount instead (path-routed
within the minecraft.mivanchenko.de block, alongside the BlueMap
failover) - no new container or mount needed. install.sh/install.ps1
MODPACK_URL updated accordingly; install scripts themselves stay on
Gitea since they're small text files. Verified full byte-exact
download end-to-end. Also drops the stale "moving to the venue"
comments now that the server is permanently on mivanchenko.de.

install.ps1

@@ -6,10 +6,10 @@
 # Participants run:    irm https://git.mivanchenko.de/mivanchenko/mc-lan-party/raw/branch/main/install.ps1 | iex
 
 # ---- EDIT ME before hosting ----
-$HostUrl      = "https://git.mivanchenko.de/mivanchenko/mc-lan-party/raw/branch/main"
-$ModpackUrl   = "$HostUrl/modpack.zip"
+$HostUrl      = "https://git.mivanchenko.de/mivanchenko/mc-lan-party/raw/branch/main"  # for this script + install.sh (small text files)
+$ModpackUrl   = "https://minecraft.mivanchenko.de/modpack.zip"  # served directly by Caddy (static/ mount), NOT Gitea — modpack.zip is well over Gitea's 50MB upload cap
 $InstanceName = "LANParty"
-$ServerAddr   = "minecraft.mivanchenko.de:25565"  # DNS name, not a raw IP — repoint the A record instead of rebuilding modpack.zip. See HOSTING.md "Moving the server to the venue".
+$ServerAddr   = "minecraft.mivanchenko.de:25565"  # always-on homelab box, same address for prep and the actual party
 # ---------------------------------
 
 $ErrorActionPreference = "Stop"  # fail loudly instead of printing an error and silently continuing