Every base-URL env var a provider's SDK may read.
Element [0] is the canonical name ā the one we write a stored endpoint to.
get_base_url reads each name in tuple order through resolve_env_var, so every
base URL gets the same DEEPAGENTS_CODE_* > plain-var precedence as API keys.
The remaining names are alternates the SDK might also honor;
apply_stored_credentials clears them when applying or resetting an endpoint, so
a stale value (e.g. an inherited gateway URL) can't leak through. Clearing every
name is what lets the write path treat the canonical as authoritative regardless
of which name the SDK prefers.
The key and its endpoint are a coherent pair: a gateway key only works against the gateway URL, a provider-native key only against the provider's own endpoint, so both must resolve from the same source.
