build(docker): add core application image

docker/core-entrypoint.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+set -eu
+
+case "${1:-server}" in
+  server)
+    shift || true
+    exec node /app/backend/dist/server.js "$@"
+    ;;
+  doctor)
+    shift
+    exec tht doctor "$@"
+    ;;
+  preprocess)
+    shift
+    exec tht preprocess "$@"
+    ;;
+  tht)
+    shift
+    exec tht "$@"
+    ;;
+  *)
+    exec tht "$@"
+    ;;
+esac