chore: back up Pi environment

assemble-pi-backup.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+# Reassemble a Git-LFS split Pi backup after `git lfs pull`.
+# Usage: ./assemble-pi-backup.sh [backup-base-name]
+
+base=${1:-pi-backup-20260714-002452.tar.zst}
+shopt -s nullglob
+parts=("${base}".part-*)
+
+(( ${#parts[@]} > 0 )) || {
+  printf 'No archive parts found for %s\n' "$base" >&2
+  exit 1
+}
+
+for command in cat sha256sum; do
+  command -v "$command" >/dev/null || {
+    printf 'Required command is unavailable: %s\n' "$command" >&2
+    exit 1
+  }
+done
+
+cat "${parts[@]}" > "$base"
+printf 'Created: %s\n' "$base"
+
+if [[ -f "${base}.sha256" ]]; then
+  sha256sum -c "${base}.sha256"
+else
+  printf 'Checksum file not found: %s.sha256\n' "$base" >&2
+fi