Add database schema information to package.json.

Used to determine if the actual schema on the database
is compatible with the version of the server we're
attempting to run.

lib/www/server/package.json

@@ -10,6 +10,9 @@
   "author": "Aaltronav s.r.o.",
   "license": "UNLICENSED",
   "private": true,
+  "config": {
+    "db_schema": "^0.1.0"
+  },
   "engines": {
     "node": ">=14.0.0"
   },