add auto-migration on backend startup

migrate.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+set -e
+
+# Load secrets into environment
+source /abra-entrypoint.sh -e
+
+# Wait for database to be ready (up to 30 seconds)
+i=0
+while ! python manage.py check --database default 2>/dev/null; do
+  i=$((i+1))
+  if [ "$i" -ge 30 ]; then
+    echo "migrate: timed out waiting for database" >&2
+    exit 1
+  fi
+  sleep 1
+done
+
+# Idempotent: skip if no pending migrations
+if python manage.py migrate --check > /dev/null 2>&1; then
+  echo "migrate: no pending migrations, skipping"
+  exit 0
+fi
+
+echo "migrate: applying pending migrations..."
+python manage.py migrate --noinput
+echo "migrate: done"