Replace direct normalize_anthropic_response() call in
_AnthropicCompletionsAdapter.create() with
AnthropicTransport.normalize_response() via get_transport().
Before: auxiliary_client called adapter v1 directly, bypassing
the transport layer entirely.
After: auxiliary_client → get_transport('anthropic_messages') →
transport.normalize_response() → adapter v1 → NormalizedResponse.
The adapter v1 function (normalize_anthropic_response) now has
zero callers outside agent/anthropic_adapter.py and the transport.
This unblocks collapsing v1 to return NormalizedResponse directly
in a follow-up (the remaining 2-layer chain becomes 1-layer).
WS1 item 2 of Cycle 2 (#14418).
738d0900fd