Restore the SSH access in the cleanup

The key that the website logs in with lives in the home directory of the
user, so a deleted home directory took it away and the site could not
connect any more. The key is now one of the copies the cleanup restores,
and it is merged into the authorized_keys of the user, so that keys they
added stay.

The installer writes the same key for the Administrator, and the deploy
script checks that it is the key the website uses.

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

server/home/.ssh/authorized_keys

@@ -0,0 +1 @@
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIJDweEH8bhZAHVaAedhTVDb2j/oMEn3vm97xCwCw9LC9 root@nowhere.wirs.ing cygwin-2222

server/home/.zshenv

@@ -0,0 +1,3 @@
+# Preset what MSYS2's /etc/profile would otherwise start a helper process for (~90 ms each here).
+# TZ has to match the Windows timezone (W. Europe Standard Time).
+export LANG=en_US.UTF-8 TZ=Europe/Berlin

server/home/.zshrc

@@ -0,0 +1,36 @@
+# History shared between sessions.
+HISTFILE=~/.zsh_history HISTSIZE=10000 SAVEHIST=10000
+setopt share_history hist_ignore_dups hist_ignore_space interactive_comments auto_cd
+
+# Completion: menu, case-insensitive, colored. -C skips compaudit, which is slow on
+# Windows and meaningless under MSYS2's noacl mounts (rm ~/.zcompdump after adding completions).
+autoload -Uz compinit && compinit -C
+zstyle ':completion:*' menu select
+zstyle ':completion:*' matcher-list 'm:{a-z}={A-Z}'
+zstyle ':completion:*' list-colors ${(s.:.)LS_COLORS}
+
+# Emacs keys; Up/Down search history for what is already typed.
+bindkey -e
+autoload -Uz up-line-or-beginning-search down-line-or-beginning-search
+zle -N up-line-or-beginning-search && zle -N down-line-or-beginning-search
+bindkey '^[[A' up-line-or-beginning-search '^[OA' up-line-or-beginning-search
+bindkey '^[[B' down-line-or-beginning-search '^[OB' down-line-or-beginning-search
+
+# Prompt: user@host:directory, git branch, exit status of the last command if it failed.
+# A literal '#' as on Linux: zsh's %# would show '%', since this root is not uid 0.
+# The branch is read from .git/HEAD directly: starting git on every prompt is slow on Windows.
+precmd() {
+  local d=$PWD head=
+  until [[ -e $d/.git || $d == / ]]; do d=${d:h}; done
+  [[ -f $d/.git/HEAD ]] && read -r head < $d/.git/HEAD
+  [[ $head == 'ref: '* ]] && git_branch=${head#ref: refs/heads/} || git_branch=${head:0:7}
+  print -Pn '\e]0;%n@%m: %~\a'
+}
+setopt prompt_subst
+PROMPT='%F{green}%n@%m%f:%F{blue}%~%f${git_branch:+ %5F($git_branch)%f}%(?.. %F{red}[%?]%f)# '
+
+alias ls='ls --color=auto' ll='ls -lah' grep='grep --color=auto'
+
+# Process monitor: htop does not exist for MSYS2 (its /proc only shows MSYS2 processes).
+# bottom is a native Windows program; winpty lets it draw in the pty, as Server 2016 has no ConPTY.
+alias btm='winpty /ucrt64/bin/btm'