Add enhanced uncaught error logging, allow internal networking for API communication

[efstajas]

Adds a new CODEGEN_GQL_URL env var (defaults to value of GQL_URL), which allows using the public API endpoint for codegen, but use an internal URL for actual app <> api communcation at runtime. This is necessary because railway private networking does not work at build time.

Also changes dripsQL to query the api proxy endpoint on localhost rather than BASE_URL, but only server-side in prod. This avoids network overhead when the server calls itself during SSR.

Lastly, adds console logging on uncaught exceptions (incl. Fetch failed), and adds a check for API being reachable to health endpoint.

Release plan:

1. Set CODEGEN_GQL_URL to public GQL API URL (https)
2. Merge this PR, let it deploy. App will continue talking to public API URL.
3. Change GQL_URL to private GQL API URL (http) at port 8080.

[railway-app]

🚅 Previously deployed to Railway in the Drips App project. Environment has been deleted.