feat(gost): require upstream proxy for geo-bypass

gost now always requires an external upstream proxy to function.
wizard prompts for upstream proxy url when gost is selected.
if no upstream provided, gost is removed from selection.

docker-compose.yml

@@ -356,6 +356,8 @@ services:
     command:
       - "-L"
       - "http://${GOST_USERNAME}:${GOST_PASSWORD}@:8080"
+      - "-F"
+      - "${GOST_UPSTREAM_PROXY}"
     healthcheck:
       test: ["CMD-SHELL", "wget -q --spider http://localhost:8080 || exit 1"]
       interval: 30s