Add means to configure front-end app via Environment Variables #10
Description
In order to make it easier for self-hosters to run the app under their setup the front-end app needs to be able to be configured via Environment Variables. The folliwing parts of the front-end should be configurable:
- Back-end URL
- PostHog URL or if not defined then analytics is disabled
- Sentry/GlitchTup URL or if not defined then observability is disabled