feat: install esbuild and configure

[scheidtdav]

This PR introduces esbuild for building and bundling the application.
Here is a quick comparison between building with tsc vs. building with esbuild:

tsc:

• Requires node_modules in container
• faster cold start time due to smaller files
• easier debugging (no minification, original file structure)
• Total: node_modules + code = ~120MB

esbuild:

• Single file deployment (only index.js)
• Fast build times
• extensionless imports (just like in browser projects)
• Total: just required code ~1.6MB

@jona159 What do we want? 🤔 I am not super sure whats the best way.