refactor: reduce cyclomatic complexity (30 functions exceed threshold of 20)

[Oaklight]

Background

Complexipy was added to pre-commit in commit 10644a8 but is currently suspended because 30 functions in the codebase exceed the complexity threshold of 20.

The hook will be re-enabled once these are resolved:

entry: complexipy src/llm_rosetta tests -e _vendor -mx 20

Violations (sorted by complexity, descending)

Function	Complexity
fix_orphaned_tool_calls (openai_chat/tool_ops)	43
_Socks5Handler::_do_handshake (tests/gateway)	40
sanitize_request_data (gateway/logging)	38
OpenAIChatMessageOps::_unpack_tool_content	37
_stream_event_generator (gateway/proxy)	37
fix_orphaned_tool_calls_ir	36
OpenAIResponsesToolOps::ir_tool_call_to_p	33
GoogleGenAIMessageOps::_reconcile_tool_call_ids	33
sanitize_schema	30
_proxy_handler (gateway/app)	30
OpenAIResponsesToolOps::p_tool_call_to_ir	30
_collect_ir_tool_ids	30
OpenAIResponsesMessageOps::p_messages_to_ir	29
OpenAIResponsesConverter::_capture_preserve_metadata	29
OpenAIResponsesConverter::_apply_preserve_metadata	29
OpenAIChatMessageOps::_reorder_tool_messages	29
fix_orphaned_tool_calls (openai_responses/tool_ops)	26
fetch_upstream_models (gateway/admin/routes/config)	26
GoogleGenAIConverter::stream_response_from_provider	25
GoogleGenAIConverter::request_to_provider	25
call_api_stream (tests/integration, ×2)	25
OpenAIChatConverter::_handle_tool_calls_from_p	24
create_auth_hook (gateway/auth)	24
AnthropicConverter::request_to_provider	24
GoogleGenAIMessageOps::_p_message_to_ir	23
GatewayConfig::__init__ (gateway/config)	22
fix_orphaned_tool_calls (anthropic/tool_ops)	22
AnthropicConverter::request_from_provider	22
GoogleGenAIContentOps::p_part_to_ir	21

Definition of done

• All functions reduced to complexity ≤ 20 (ideally ≤ 15)
• Complexipy hook re-enabled in .pre-commit-config.yaml
• pre-commit run complexipy --all-files exits 0