Fix docker setup

Author: Kagemaru

.docker/entrypoint.sh

@@ -2,6 +2,7 @@
 
 set -e
 
+gem install bundler
 bundle install
 
 bin/rails db:migrate RAILS_ENV=development

.docker/webpack-entrypoint.sh

@@ -2,6 +2,7 @@
 
 set -e
 
+yarn add webpack-dev-server@4.15.1 --dev
 yarn install
 
 exec "$@"

package.json

@@ -57,6 +57,7 @@
     "marked": "^5.1.2",
     "prettier": "^3.3.3",
     "select2": "^4.1.0-rc.0",
-    "stylelint": "^13.11.0"
+    "stylelint": "^13.11.0",
+    "webpack-dev-server": "4.15.1"
   }
 }