Providers that read credentials from several environment variables
(Bedrock, Azure, Vertex) never get a single resolved Provider.key from
OpenCode, so dropping the env signal made them show "Credentials
missing", auto-open the auth panel, and hide their models even when
fully configured.
providerHasCredentials takes an envDeclared input again, and both
call sites in ProvidersPage pass whether the provider declares any
non-empty env var name.
Bohdan Triapitsyn
c788cd2237