refactor: new dev/prod containers

- Use a single Dockerfile for all Zeppelin services
- Add a Dockerfile in project root that can be used by
  app hosting services
- Provide a standalone and lightweight prod setup
  - Standalone is the same as the old setup, with mysql+nginx
  - Lightweight only runs bot+backend+dash, no mysql/nginx
- Remove mounted mysql data folders for dev and prod
  - This resolves permission issues caused by the mount
  - The mysql service uses a regular named volume now
- Simplify .env options and clearly separate different prod setups
- Remove update.sh
  - Different setups require different update procedures, so a common
    update.sh no longer works

Dockerfile

@@ -0,0 +1,20 @@
+FROM node:20
+USER node
+
+COPY --chown=node:node . /zeppelin
+
+# Install dependencies for all packages
+WORKDIR /zeppelin
+RUN npm ci
+
+# Build backend
+WORKDIR /zeppelin/backend
+RUN npm run build
+
+# Build dashboard
+WORKDIR /zeppelin/dashboard
+RUN npm run build
+
+# Prune dev dependencies
+WORKDIR /zeppelin
+RUN npm prune --production