Improve environment variable handling and reading (#5389)

* wip: better env var reading

* move most env vars to env.rs

* migrate more env vars

* more migration

* more migrations

* More migration

* 🦀 dotenvy is gone (almost)

* 🦀 dotenvy is gone 🦀

* Fix mural source account env var handling

* Remove defaults from admin key vars

* dummy commit to update github pr

* fix ci

apps/labrinth/src/routes/updates.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 
 use crate::database::PgPool;
+use crate::env::ENV;
 use actix_web::{HttpRequest, HttpResponse, get, web};
 use serde::{Deserialize, Serialize};
 
@@ -94,11 +95,7 @@ pub async fn forge_updates(
     }
 
     let mut response = ForgeUpdates {
-        homepage: format!(
-            "{}/mod/{}",
-            dotenvy::var("SITE_URL").unwrap_or_default(),
-            id
-        ),
+        homepage: format!("{}/mod/{}", ENV.SITE_URL, id),
         promos: HashMap::new(),
     };