Fix auth prompt logic for SDK v0.126.0 host-type changes

The SDK removed host-type validation from NewAccountClient/NewWorkspaceClient
in favor of host metadata resolution. This broke the CLI's auth prompt logic
which relied on ErrNotAccountClient/ErrNotWorkspaceClient sentinels.

Fixes:
- Use cfg.HostType() instead of cfg.ConfigType() to detect wrong host type,
  with explicit handling for UnifiedHost
- Synthesize ErrNotAccountClient/ErrNotWorkspaceClient when the config is
  for the wrong host type and prompting is unavailable, preserving the
  MustAnyClient fallthrough and giving actionable errors
- Add tests for wrong-type configs with prompting disabled
- Fix noNetworkTransport comment and MustAnyClient comment

Also fix whitespace in generated environments.go.

Co-authored-by: Isaac

Author: simonfaltum