Add polling deployment scripts

cd-watch.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+set -eu
+
+APP_DIR="$(cd "$(dirname "$0")" && pwd)"
+STATE_FILE="$APP_DIR/data/deployed-rev"
+LOG_FILE="$APP_DIR/data/deploy.log"
+
+mkdir -p "$APP_DIR/data"
+cd "$APP_DIR"
+
+remote_rev="$(git ls-remote origin refs/heads/main | awk '{print $1}')"
+if [ -z "$remote_rev" ]; then
+  echo "$(date '+%Y-%m-%d %H:%M:%S') no remote revision found" >> "$LOG_FILE"
+  exit 1
+fi
+
+current_rev=""
+[ -f "$STATE_FILE" ] && current_rev="$(cat "$STATE_FILE")"
+
+if [ "$remote_rev" = "$current_rev" ]; then
+  exit 0
+fi
+
+echo "$(date '+%Y-%m-%d %H:%M:%S') change detected $current_rev -> $remote_rev" >> "$LOG_FILE"
+"$APP_DIR/deploy.sh"
+printf '%s\n' "$remote_rev" > "$STATE_FILE"