Generalize the remote tooling check to a list of required commands

Per-run tooling verification (added in the previous commit) was hardcoded
to checking just `nix`. Turn it into a small array instead, so a future
remote build step needing another tool extends that list rather than
growing a second parallel check.

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

scripts/create-proxmox-resource.sh

@@ -544,18 +544,29 @@ ensure_remote_repo() {
     ssh "$ssh_target" "git clone '${origin_url}' '${remote_repo_dir}'"
   fi
 
-  # Checked (and bootstrapped if missing) every run, not just right after a
-  # fresh clone -- confirmed live: a first bootstrap can clone the repo
-  # successfully and still leave the node without a working `nix` (e.g. the
-  # node had no `sudo`, which the Nix installer's root path depends on --
-  # see the fix in scripts/codex-setup.sh), and a later run with the repo
-  # already present would otherwise never retry it. Sources
-  # scripts/lib/nix-bootstrap.sh's ensure_nix_profile the same way the
-  # build commands below do -- a single-user Nix install typically only
-  # gets sourced into login shells, and ssh's non-interactive command
-  # execution is neither, so a freshly-installed `nix` still wouldn't be on
-  # PATH here without it.
-  if ssh "$ssh_target" "cd '${remote_repo_dir}' && . scripts/lib/nix-bootstrap.sh && ensure_nix_profile && command -v nix" >/dev/null 2>&1; then
+  # Trivial check, run every time (not just right after a fresh clone) --
+  # confirmed live: a first bootstrap can clone the repo successfully and
+  # still leave the node without a working `nix` (e.g. the node had no
+  # `sudo`, which the Nix installer's root path depends on -- see the fix
+  # in scripts/codex-setup.sh), and a later run with the repo already
+  # present would otherwise never retry it. Sources
+  # scripts/lib/nix-bootstrap.sh's ensure_nix_profile first -- a
+  # single-user Nix install typically only gets sourced into login shells,
+  # and ssh's non-interactive command execution is neither, so a
+  # freshly-installed `nix` still wouldn't be on PATH here without it.
+  #
+  # Just `nix` today -- the only thing the remote build commands below
+  # actually invoke -- but a list (not a single hardcoded check) so a
+  # future remote step needing another tool can add itself here instead of
+  # growing a parallel check.
+  local remote_required_cmds=(nix)
+  local tooling_check_cmd="cd '${remote_repo_dir}' && . scripts/lib/nix-bootstrap.sh && ensure_nix_profile"
+  local cmd
+  for cmd in "${remote_required_cmds[@]}"; do
+    tooling_check_cmd="${tooling_check_cmd} && command -v ${cmd}"
+  done
+
+  if ssh "$ssh_target" "$tooling_check_cmd" >/dev/null 2>&1; then
     echo "Build tooling already present on ${node}."
   else
     echo "==> Bootstrapping build tooling on ${node} (scripts/codex-setup.sh)..."