feat: add Pi monitoring stack with deployment scripts and architecture documentation

setup/pi-monitoring/restore_stack.sh

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck source=./lib.sh
+source "$SCRIPT_DIR/lib.sh"
+
+ARCHIVE=""
+AUTO_YES=false
+
+usage() {
+  cat <<USAGE
+Usage: $(basename "$0") --archive=/path/to/pi-monitoring-*.tar.gz [options]
+
+Restore monitoring stack data/config from a backup archive created by backup_stack.sh.
+
+Options:
+  --archive=PATH   Backup archive to restore (required)
+  --yes, -y        Skip confirmation prompt
+  --help, -h       Show help
+USAGE
+}
+
+for arg in "$@"; do
+  case "$arg" in
+    --archive=*) ARCHIVE="${arg#*=}" ;;
+    --yes|-y) AUTO_YES=true ;;
+    --help|-h) usage; exit 0 ;;
+    *) log_error "Unknown argument: $arg"; usage; exit 1 ;;
+  esac
+done
+
+require_cmd tar
+
+if [[ -z "$ARCHIVE" ]]; then
+  log_error "--archive is required"
+  usage
+  exit 1
+fi
+
+if [[ ! -f "$ARCHIVE" ]]; then
+  log_error "Archive not found: $ARCHIVE"
+  exit 1
+fi
+
+if ! confirm_action "Restore from $ARCHIVE? Existing stack data may be overwritten." "$AUTO_YES"; then
+  log_info "Cancelled"
+  exit 0
+fi
+
+log_info "Stopping compose services before restore (best effort)..."
+if [[ -f "$SCRIPT_DIR/stack.env" ]]; then
+  load_stack_env "$SCRIPT_DIR/stack.env"
+  docker compose \
+    --project-name "$COMPOSE_PROJECT_NAME" \
+    --env-file "$SCRIPT_DIR/stack.env" \
+    -f "$(compose_file)" \
+    down || true
+fi
+
+log_info "Extracting backup archive to / ..."
+sudo tar -xzf "$ARCHIVE" -C /
+
+log_success "Restore complete"
+log_info "Run deploy_stack.sh to bring services back up"