feat(server): a deliberate powerlevel10k prompt instead of the wizard's

p10k is now installed on shron, so the red prompt the role split was built
around finally applies to the machine it was meant for. Cloned into
$ZSH_CUSTOM/themes rather than installed as a package: no root, nothing outside
the user's home, and undone by deleting a directory.

Without a configuration p10k runs its setup wizard on the first interactive
shell. Over SSH that is a login that sits there waiting for an answer, so the
server gets a written configuration and the wizard is disabled outright.

It is not a copy of beastix's. That one assumes a Nerd Font and a wide
terminal; a server is reached from whatever is at hand, so this uses ASCII,
one line, and a short segment list. user@host is always shown, on red - which
is the whole point.

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

.config/zsh/rc.d/50-server.zsh

@@ -3,15 +3,14 @@
 # The theme and DISABLE_AUTO_UPDATE are in 05-pre-omz.zsh, because oh-my-zsh
 # reads them while it is being sourced.
 
-# Role colour, set here rather than earlier because ~/.p10k.zsh assigns
-# POWERLEVEL9K_CONTEXT_BACKGROUND itself and is sourced in 30-path.zsh.
+# The prompt, in a file of its own because there is more to it than a colour.
+# Sourced here rather than earlier: this is the point at which oh-my-zsh has
+# loaded powerlevel10k, which is where p10k expects its configuration.
 #
-# Note that this only takes effect where powerlevel10k is installed, and on
-# shron it is not - the ys theme has no equivalent. The colour is kept anyway
-# so it works the moment p10k arrives, but the red prompt cannot be relied on
-# as a safeguard there today.
-typeset -g POWERLEVEL9K_CONTEXT_BACKGROUND=red
-typeset -g POWERLEVEL9K_ALWAYS_SHOW_CONTEXT=true
+# beastix keeps its own ~/.p10k.zsh, sourced from 30-path.zsh. This one is
+# separate because a server is reached from whatever terminal is at hand and
+# cannot assume the desktop's Nerd Font.
+[[ -r "$HOME/.config/zsh/p10k-server.zsh" ]] && source "$HOME/.config/zsh/p10k-server.zsh"
 
 # German locale. The base does not set one, since the desktop inherits it from
 # the session and the Mac has its own; an SSH session brings only what the