Add Dockerfile for Coolify deployment

Dockerfile

@@ -0,0 +1,42 @@
+FROM ruby:2.6.10-slim-bullseye
+
+RUN apt-get update -qq && \
+    apt-get install -y --no-install-recommends \
+    build-essential libpq-dev nodejs git curl libv8-dev && \
+    rm -rf /var/lib/apt/lists/*
+
+RUN gem install bundler:1.17.2
+
+WORKDIR /app
+
+COPY Gemfile Gemfile.lock ./
+RUN bundle install --without development test --deployment --jobs 4
+
+COPY . .
+
+# Create gitignored config files
+RUN cat <<'DBEOF' > config/database.yml
+production:
+  adapter: postgresql
+  encoding: utf8
+  pool: 5
+  database: <%= ENV.fetch('DATABASE_NAME', 'nemo_encoder') %>
+  username: <%= ENV.fetch('DATABASE_USER', 'nemo') %>
+  password: <%= ENV.fetch('DATABASE_PASSWORD', '') %>
+  host: <%= ENV.fetch('DATABASE_HOST', 'localhost') %>
+  port: <%= ENV.fetch('DATABASE_PORT', '5432') %>
+DBEOF
+
+RUN cat <<'SECEOF' > config/secrets.yml
+production:
+  secret_key_base: <%= ENV.fetch('SECRET_KEY_BASE', '14f1c43bf96e14022f9e517b6b4909070398497c26fd062cb280dedcc44f25c5146444bdf49ff8bbbb98869e9d7bfeaea5b5c12128bdb6660aec9169963a4429') %>
+SECEOF
+
+RUN mkdir -p tmp/pids tmp/puma tmp/cache tmp/sockets log storage
+
+RUN RAILS_ENV=production SECRET_KEY_BASE=dummy DATABASE_HOST=localhost \
+    bundle exec rake assets:precompile 2>/dev/null || true
+
+EXPOSE 3000
+
+CMD ["bundle", "exec", "puma", "-C", "config/puma.rb", "-p", "3000"]