Doing mix assets.deploy after integrating LiveSvelte

Hmm, the LiveSvelte docs mentions adding RUN npm install to the Dockerfile.

2. Modify the generated Dockerfile to install curl, which is used to install nodejs (version 19 or greater), and also add a step to install our npm dependencies:
...
+ # install all npm packages in assets directory
+ WORKDIR /app/assets
+ RUN npm install

source: Deployment: Deploying on Fly.io | LiveSvelte Readme