Build Proxmox images directly on the node instead of transferring them

create-proxmox-resource.sh no longer builds locally and scp's a
multi-gigabyte image over -- it now clones/pulls this repo onto the
Proxmox node itself (bootstrapping build tooling via the existing
codex-setup.sh on first use) and runs the nix build / disko image
script there, staging the result straight into the node's own import
directory. host-keys/ (gitignored) is copied over separately since a
git pull doesn't carry it. --image still uploads an explicit local
file for the case where you don't want a build at all.

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

scripts/env.sh

@@ -14,6 +14,14 @@
 : "${PROXMOX_HOST:=pve.sweet.home}"
 : "${PROXMOX_SSH_USER:=root}"
 
+# Where this flake repo lives on the Proxmox node itself.
+# scripts/create-proxmox-resource.sh builds images directly on the node
+# instead of transferring them over the network -- it clones the repo here
+# (from this checkout's own `origin` remote) the first time it doesn't
+# find it, installing build tooling via scripts/codex-setup.sh, then
+# `git pull`s it before every subsequent build.
+: "${PROXMOX_REMOTE_REPO_DIR:=/root/nixos}"
+
 # Storage pool names -- Proxmox's own stock-install defaults, but this
 # varies a lot by setup (ZFS pool name, custom LVM-thin volume, etc.).
 # Verify with `pvesm status` on the node and correct these if wrong.
@@ -49,7 +57,8 @@
 
 export PROXMOX_HOST PROXMOX_SSH_USER PROXMOX_STORAGE PROXMOX_ISO_STORAGE \
   PROXMOX_BRIDGE PROXMOX_DEFAULT_CORES PROXMOX_DEFAULT_MEMORY_MB \
-  PROXMOX_DEFAULT_LXC_DISK_GB PROXMOX_DEFAULT_LXC_FEATURES
+  PROXMOX_DEFAULT_LXC_DISK_GB PROXMOX_DEFAULT_LXC_FEATURES \
+  PROXMOX_REMOTE_REPO_DIR
 
 # Matches variables.nix's nixCacheHost -- update both if it ever changes.
 : "${NIX_CACHE_HOST:=nix-cache}"